meson: Move all code generation scripts to utils/codegen/

We have multiple code generation scripts in utils/, mixed with other
miscellaneous utilities, as well as a larger code base based on mojom in
utils/ipc/. To make code sharing easier between the generator scripts,
without creating a mess in the utils/ directory, move all the code
generation code to utils/codegen/.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

62 files changed, 15636 insertions, 0 deletions

diff --git a/utils/codegen/ipc/mojo/README b/utils/codegen/ipc/mojo/README
new file mode 100644
index 00000000..961cabd2
--- /dev/null
+++ b/utils/codegen/ipc/mojo/README
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: CC0-1.0
+
+Files in this directory are imported from 9be4263648d7 of Chromium. Do not
+modify them manually.
diff --git a/utils/codegen/ipc/mojo/public/LICENSE b/utils/codegen/ipc/mojo/public/LICENSE
new file mode 100644
index 00000000..513e8a6a
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/LICENSE
@@ -0,0 +1,27 @@
+// Copyright 2014 The Chromium Authors
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/utils/codegen/ipc/mojo/public/tools/.style.yapf b/utils/codegen/ipc/mojo/public/tools/.style.yapf
new file mode 100644
index 00000000..b4ebbe24
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/.style.yapf
@@ -0,0 +1,6 @@
+[style]
+based_on_style = pep8
+
+# New directories should use a .style.yapf that does not include the following:
+column_limit = 80
+indent_width = 2
diff --git a/utils/codegen/ipc/mojo/public/tools/BUILD.gn b/utils/codegen/ipc/mojo/public/tools/BUILD.gn
new file mode 100644
index 00000000..5328a34a
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/BUILD.gn
@@ -0,0 +1,22 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# The main target used to aggregate all unit tests for Python-based Mojo tools.
+# This is used to generate a complete isolate which can be pushed to bots to run
+# the tests.
+group("mojo_python_unittests") {
+  data = [
+    "run_all_python_unittests.py",
+    "//testing/scripts/run_isolated_script_test.py",
+  ]
+  deps = [
+    "//mojo/public/tools/bindings:tests",
+    "//mojo/public/tools/mojom:tests",
+    "//mojo/public/tools/mojom/mojom:tests",
+  ]
+  data_deps = [
+    "//testing:test_scripts_shared",
+    "//third_party/catapult/third_party/typ/",
+  ]
+}
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/BUILD.gn b/utils/codegen/ipc/mojo/public/tools/bindings/BUILD.gn
new file mode 100644
index 00000000..eeca73ea
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/BUILD.gn
@@ -0,0 +1,131 @@
+# Copyright 2016 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//mojo/public/tools/bindings/mojom.gni")
+import("//third_party/jinja2/jinja2.gni")
+
+action("precompile_templates") {
+  sources = mojom_generator_sources
+  sources += [
+    "$mojom_generator_root/generators/cpp_templates/cpp_macros.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/enum_macros.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/enum_serialization_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/feature_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/feature_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_feature_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_macros.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_proxy_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_request_validator_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_response_validator_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/interface_stub_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-features.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-forward.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-import-headers.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-params-data.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-shared-internal.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-shared-message-ids.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-shared.cc.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-shared.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module-test-utils.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module.cc.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/module.h.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_data_view_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_data_view_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_macros.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_serialization_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_traits_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_traits_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/struct_unserialized_message_context.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_data_view_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_data_view_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_serialization_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_traits_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/union_traits_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/validation_macros.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/wrapper_class_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/wrapper_class_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/wrapper_class_template_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/wrapper_union_class_declaration.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/wrapper_union_class_definition.tmpl",
+    "$mojom_generator_root/generators/cpp_templates/wrapper_union_class_template_definition.tmpl",
+    "$mojom_generator_root/generators/java_templates/constant_definition.tmpl",
+    "$mojom_generator_root/generators/java_templates/constants.java.tmpl",
+    "$mojom_generator_root/generators/java_templates/data_types_definition.tmpl",
+    "$mojom_generator_root/generators/java_templates/enum.java.tmpl",
+    "$mojom_generator_root/generators/java_templates/enum_definition.tmpl",
+    "$mojom_generator_root/generators/java_templates/header.java.tmpl",
+    "$mojom_generator_root/generators/java_templates/interface.java.tmpl",
+    "$mojom_generator_root/generators/java_templates/interface_definition.tmpl",
+    "$mojom_generator_root/generators/java_templates/interface_internal.java.tmpl",
+    "$mojom_generator_root/generators/java_templates/struct.java.tmpl",
+    "$mojom_generator_root/generators/java_templates/union.java.tmpl",
+    "$mojom_generator_root/generators/js_templates/enum_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/fuzzing.tmpl",
+    "$mojom_generator_root/generators/js_templates/interface_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/enum_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/enum_definition_for_module.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/interface_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/interface_definition_for_module.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/module_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/mojom-lite.js.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/mojom.m.js.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/struct_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/struct_definition_for_module.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/union_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/lite/union_definition_for_module.tmpl",
+    "$mojom_generator_root/generators/js_templates/module.amd.tmpl",
+    "$mojom_generator_root/generators/js_templates/module_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/struct_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/union_definition.tmpl",
+    "$mojom_generator_root/generators/js_templates/validation_macros.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm.cc.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm.h.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm.proto.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm_from_proto_macros.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm_macros.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm_to_proto_macros.tmpl",
+    "$mojom_generator_root/generators/mojolpm_templates/mojolpm_traits_specialization_macros.tmpl",
+    "$mojom_generator_root/generators/ts_templates/enum_definition.tmpl",
+    "$mojom_generator_root/generators/ts_templates/interface_definition.tmpl",
+    "$mojom_generator_root/generators/ts_templates/module_definition.tmpl",
+    "$mojom_generator_root/generators/ts_templates/struct_definition.tmpl",
+    "$mojom_generator_root/generators/ts_templates/union_definition.tmpl",
+  ]
+  script = mojom_generator_script
+
+  inputs = jinja2_sources
+  outputs = [
+    "$target_gen_dir/cpp_templates.zip",
+    "$target_gen_dir/java_templates.zip",
+    "$target_gen_dir/js_templates.zip",
+    "$target_gen_dir/mojolpm_templates.zip",
+    "$target_gen_dir/ts_templates.zip",
+  ]
+  args = [
+    "-o",
+    rebase_path(target_gen_dir, root_build_dir),
+    "--use_bundled_pylibs",
+    "precompile",
+  ]
+}
+
+group("tests") {
+  data = [
+    mojom_generator_script,
+    "checks/mojom_attributes_check_unittest.py",
+    "checks/mojom_interface_feature_check_unittest.py",
+    "checks/mojom_restrictions_checks_unittest.py",
+    "mojom_bindings_generator_unittest.py",
+    "//tools/diagnosis/crbug_1001171.py",
+    "//third_party/markupsafe/",
+  ]
+  data += mojom_generator_sources
+  data += jinja2_sources
+}
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/README.md b/utils/codegen/ipc/mojo/public/tools/bindings/README.md
new file mode 100644
index 00000000..b27b2d01
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/README.md
@@ -0,0 +1,1014 @@
+# Mojom Interface Definition Language (IDL)
+This document is a subset of the [Mojo documentation](/mojo/README.md).
+
+[TOC]
+
+## Overview
+
+Mojom is the IDL for Mojo interfaces. Given a `.mojom` file, the
+[bindings
+generator](https://cs.chromium.org/chromium/src/mojo/public/tools/bindings/) can
+output bindings for any supported language: **C++**, **JavaScript**, or
+**Java**.
+
+For a trivial example consider the following hypothetical Mojom file we write to
+`//services/widget/public/mojom/frobinator.mojom`:
+
+```
+module widget.mojom;
+
+interface Frobinator {
+  Frobinate();
+};
+```
+
+This defines a single [interface](#Interfaces) named `Frobinator` in a
+[module](#Modules) named `widget.mojom` (and thus fully qualified in Mojom as
+`widget.mojom.Frobinator`.) Note that many interfaces and/or other types of
+definitions (structs, enums, *etc.*) may be included in a single Mojom file.
+
+If we add a corresponding GN target to
+`//services/widget/public/mojom/BUILD.gn`:
+
+```
+import("mojo/public/tools/bindings/mojom.gni")
+
+mojom("mojom") {
+  sources = [
+    "frobinator.mojom",
+  ]
+}
+```
+
+and then build this target:
+
+```
+ninja -C out/r services/widget/public/mojom
+```
+
+we'll find several generated sources in our output directory:
+
+```
+out/r/gen/services/widget/public/mojom/frobinator.mojom.cc
+out/r/gen/services/widget/public/mojom/frobinator.mojom.h
+out/r/gen/services/widget/public/mojom/frobinator.mojom-shared.h
+etc...
+```
+
+Each of these generated source modules includes a set of definitions
+representing the Mojom contents in C++. You can also build or depend on suffixed
+target names to get bindings for other languages. For example,
+
+```
+ninja -C out/r services/widget/public/mojom:mojom_js
+ninja -C out/r services/widget/public/mojom:mojom_java
+```
+
+would generate JavaScript and Java bindings respectively, in the same generated
+output directory.
+
+For more details regarding the generated
+outputs please see
+[documentation for individual target languages](#Generated-Code-For-Target-Languages).
+
+## Mojom Syntax
+
+Mojom IDL allows developers to define **structs**, **unions**, **interfaces**,
+**constants**, and **enums**, all within the context of a **module**. These
+definitions are used to generate code in the supported target languages at build
+time.
+
+Mojom files may **import** other Mojom files in order to reference their
+definitions.
+
+### Primitive Types
+Mojom supports a few basic data types which may be composed into structs or used
+for message parameters.
+
+| Type                          | Description
+|-------------------------------|-------------------------------------------------------|
+| `bool`                        | Boolean type (`true` or `false`.)
+| `int8`, `uint8`               | Signed or unsigned 8-bit integer.
+| `int16`, `uint16`             | Signed or unsigned 16-bit integer.
+| `int32`, `uint32`             | Signed or unsigned 32-bit integer.
+| `int64`, `uint64`             | Signed or unsigned 64-bit integer.
+| `float`, `double`             | 32- or 64-bit floating point number.
+| `string`                      | UTF-8 encoded string.
+| `array<T>`                    | Array of any Mojom type *T*; for example, `array<uint8>` or `array<array<string>>`.
+| `array<T, N>`                 | Fixed-length array of any Mojom type *T*. The parameter *N* must be an integral constant.
+| `map<S, T>`                   | Associated array mapping values of type *S* to values of type *T*. *S* may be a `string`, `enum`, or numeric type.
+| `handle`                      | Generic Mojo handle. May be any type of handle, including a wrapped native platform handle.
+| `handle<message_pipe>`        | Generic message pipe handle.
+| `handle<shared_buffer>`       | Shared buffer handle.
+| `handle<data_pipe_producer>`  | Data pipe producer handle.
+| `handle<data_pipe_consumer>`  | Data pipe consumer handle.
+| `handle<platform>`            | A native platform/OS handle.
+| *`pending_remote<InterfaceType>`*             | Any user-defined Mojom interface type. This is sugar for a strongly-typed message pipe handle which should eventually be used to make outgoing calls on the interface.
+| *`pending_receiver<InterfaceType>`*            | A pending receiver for any user-defined Mojom interface type. This is sugar for a more strongly-typed message pipe handle which is expected to receive request messages and should therefore eventually be bound to an implementation of the interface.
+| *`pending_associated_remote<InterfaceType>`*  | An associated interface handle. See [Associated Interfaces](#Associated-Interfaces)
+| *`pending_associated_receiver<InterfaceType>`* | A pending associated receiver. See [Associated Interfaces](#Associated-Interfaces)
+| *T*?                          | An optional (nullable) value. Primitive numeric types (integers, floats, booleans, and enums) are not nullable. All other types are nullable.
+
+### Modules
+
+Every Mojom file may optionally specify a single **module** to which it belongs.
+
+This is used strictly for aggregating all defined symbols therein within a
+common Mojom namespace. The specific impact this has on generated bindings code
+varies for each target language. For example, if the following Mojom is used to
+generate bindings:
+
+```
+module business.stuff;
+
+interface MoneyGenerator {
+  GenerateMoney();
+};
+```
+
+Generated C++ bindings will define a class interface `MoneyGenerator` in the
+`business::stuff` namespace, while Java bindings will define an interface
+`MoneyGenerator` in the `org.chromium.business.stuff` package. JavaScript
+bindings at this time are unaffected by module declarations.
+
+**NOTE:** By convention in the Chromium codebase, **all** Mojom files should
+declare a module name with at least (and preferably exactly) one top-level name
+as well as an inner `mojom` module suffix. *e.g.*, `chrome.mojom`,
+`business.mojom`, *etc.*
+
+This convention makes it easy to tell which symbols are generated by Mojom when
+reading non-Mojom code, and it also avoids namespace collisions in the fairly
+common scenario where you have a real C++ or Java `Foo` along with a
+corresponding Mojom `Foo` for its serialized representation.
+
+### Imports
+
+If your Mojom references definitions from other Mojom files, you must **import**
+those files. Import syntax is as follows:
+
+```
+import "services/widget/public/mojom/frobinator.mojom";
+```
+
+Import paths are always relative to the top-level directory.
+
+Note that circular imports are **not** supported.
+
+### Structs
+
+Structs are defined using the **struct** keyword, and they provide a way to
+group related fields together:
+
+``` cpp
+struct StringPair {
+  string first;
+  string second;
+};
+```
+
+Struct fields may be comprised of any of the types listed above in the
+[Primitive Types](#Primitive-Types) section.
+
+Default values may be specified as long as they are constant:
+
+``` cpp
+struct Request {
+  int32 id = -1;
+  string details;
+};
+```
+
+What follows is a fairly
+comprehensive example using the supported field types:
+
+``` cpp
+struct StringPair {
+  string first;
+  string second;
+};
+
+enum AnEnum {
+  kYes,
+  kNo
+};
+
+interface SampleInterface {
+  DoStuff();
+};
+
+struct AllTheThings {
+  // Note that these types can never be marked nullable!
+  bool boolean_value;
+  int8 signed_8bit_value = 42;
+  uint8 unsigned_8bit_value;
+  int16 signed_16bit_value;
+  uint16 unsigned_16bit_value;
+  int32 signed_32bit_value;
+  uint32 unsigned_32bit_value;
+  int64 signed_64bit_value;
+  uint64 unsigned_64bit_value;
+  float float_value_32bit;
+  double float_value_64bit;
+  AnEnum enum_value = AnEnum.kYes;
+
+  // Strings may be nullable.
+  string? maybe_a_string_maybe_not;
+
+  // Structs may contain other structs. These may also be nullable.
+  StringPair some_strings;
+  StringPair? maybe_some_more_strings;
+
+  // In fact structs can also be nested, though in practice you must always make
+  // such fields nullable -- otherwise messages would need to be infinitely long
+  // in order to pass validation!
+  AllTheThings? more_things;
+
+  // Arrays may be templated over any Mojom type, and are always nullable:
+  array<int32> numbers;
+  array<int32>? maybe_more_numbers;
+
+  // Arrays of arrays of arrays... are fine.
+  array<array<array<AnEnum>>> this_works_but_really_plz_stop;
+
+  // The element type may be nullable if it's a type which is allowed to be
+  // nullable.
+  array<AllTheThings?> more_maybe_things;
+
+  // Fixed-size arrays get some extra validation on the receiving end to ensure
+  // that the correct number of elements is always received.
+  array<uint64, 2> uuid;
+
+  // Maps follow many of the same rules as arrays. Key types may be any
+  // non-handle, non-collection type, and value types may be any supported
+  // struct field type. Maps may also be nullable.
+  map<string, int32> one_map;
+  map<AnEnum, string>? maybe_another_map;
+  map<StringPair, AllTheThings?>? maybe_a_pretty_weird_but_valid_map;
+  map<StringPair, map<int32, array<map<string, string>?>?>?> ridiculous;
+
+  // And finally, all handle types are valid as struct fields and may be
+  // nullable. Note that interfaces and interface requests (the "Foo" and
+  // "Foo&" type syntax respectively) are just strongly-typed message pipe
+  // handles.
+  handle generic_handle;
+  handle<data_pipe_consumer> reader;
+  handle<data_pipe_producer>? maybe_writer;
+  handle<shared_buffer> dumping_ground;
+  handle<message_pipe> raw_message_pipe;
+  pending_remote<SampleInterface>? maybe_a_sample_interface_client_pipe;
+  pending_receiver<SampleInterface> non_nullable_sample_pending_receiver;
+  pending_receiver<SampleInterface>? nullable_sample_pending_receiver;
+  pending_associated_remote<SampleInterface> associated_interface_client;
+  pending_associated_receiver<SampleInterface> associated_pending_receiver;
+  pending_associated_receiver<SampleInterface>? maybe_another_pending_receiver;
+};
+```
+
+For details on how all of these different types translate to usable generated
+code, see
+[documentation for individual target languages](#Generated-Code-For-Target-Languages).
+
+### Unions
+
+Mojom supports tagged unions using the **union** keyword. A union is a
+collection of fields which may take the value of any single one of those fields
+at a time. Thus they provide a way to represent a variant value type while
+minimizing storage requirements.
+
+Union fields may be of any type supported by [struct](#Structs) fields. For
+example:
+
+```cpp
+union ExampleUnion {
+  string str;
+  StringPair pair;
+  int64 id;
+  array<uint64, 2> guid;
+  SampleInterface iface;
+};
+```
+
+For details on how unions like this translate to generated bindings code, see
+[documentation for individual target languages](#Generated-Code-For-Target-Languages).
+
+### Enumeration Types
+
+Enumeration types may be defined using the **enum** keyword either directly
+within a module or nested within the namespace of some struct or interface:
+
+```
+module business.mojom;
+
+enum Department {
+  kSales = 0,
+  kDev,
+};
+
+struct Employee {
+  enum Type {
+    kFullTime,
+    kPartTime,
+  };
+
+  Type type;
+  // ...
+};
+```
+
+C++ constant-style enum value names are preferred as specified in the
+[Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html#Enumerator_Names).
+
+Similar to C-style enums, individual values may be explicitly assigned within an
+enum definition. By default, values are based at zero and increment by
+1 sequentially.
+
+The effect of nested definitions on generated bindings varies depending on the
+target language. See [documentation for individual target languages](#Generated-Code-For-Target-Languages).
+
+### Constants
+
+Constants may be defined using the **const** keyword either directly within a
+module or nested within the namespace of some struct or interface:
+
+```
+module business.mojom;
+
+const string kServiceName = "business";
+
+struct Employee {
+  const uint64 kInvalidId = 0;
+
+  enum Type {
+    kFullTime,
+    kPartTime,
+  };
+
+  uint64 id = kInvalidId;
+  Type type;
+};
+```
+
+The effect of nested definitions on generated bindings varies depending on the
+target language. See [documentation for individual target languages](#Generated-Code-For-Target-Languages).
+
+### Features
+
+Features can be declared with a `name` and `default_state` and can be attached
+in mojo to interfaces or methods using the `RuntimeFeature` attribute. If the
+feature is disabled at runtime, the method will crash and the interface will
+refuse to be bound / instantiated. Features cannot be serialized to be sent over
+IPC at this time.
+
+```
+module experimental.mojom;
+
+feature kUseElevators {
+  const string name = "UseElevators";
+  const bool default_state = false;
+}
+
+[RuntimeFeature=kUseElevators]
+interface Elevator {
+  // This interface cannot be bound or called if the feature is disabled.
+}
+
+interface Building {
+  // This method cannot be called if the feature is disabled.
+  [RuntimeFeature=kUseElevators]
+  CallElevator(int floor);
+
+  // This method can be called.
+  RingDoorbell(int volume);
+}
+```
+
+### Interfaces
+
+An **interface** is a logical bundle of parameterized request messages. Each
+request message may optionally define a parameterized response message. Here's
+an example to define an interface `Foo` with various kinds of requests:
+
+```
+interface Foo {
+  // A request which takes no arguments and expects no response.
+  MyMessage();
+
+  // A request which has some arguments and expects no response.
+  MyOtherMessage(string name, array<uint8> bytes);
+
+  // A request which expects a single-argument response.
+  MyMessageWithResponse(string command) => (bool success);
+
+  // A request which expects a response with multiple arguments.
+  MyMessageWithMoarResponse(string a, string b) => (int8 c, int8 d);
+};
+```
+
+Anything which is a valid struct field type (see [Structs](#Structs)) is also a
+valid request or response argument type. The type notation is the same for both.
+
+### Attributes
+
+Mojom definitions may have their meaning altered by **attributes**, specified
+with a syntax similar to Java or C# attributes. There are a handle of
+interesting attributes supported today.
+
+* **`[Sync]`**:
+  The `Sync` attribute may be specified for any interface method which expects a
+  response. This makes it so that callers of the method can wait synchronously
+  for a response. See [Synchronous
+  Calls](/mojo/public/cpp/bindings/README.md#Synchronous-Calls) in the C++
+  bindings documentation. Note that sync methods are only actually synchronous
+  when called from C++.
+
+* **`[NoInterrupt]`**:
+  When a thread is waiting for a reply to a `Sync` message, it's possible to be
+  woken up to dispatch other unrelated incoming `Sync` messages. This measure
+  helps to avoid deadlocks. If a `Sync` message is also marked as `NoInterrupt`
+  however, this behavior is disabled: instead the calling thread will only wake
+  up for the precise message being waited upon. This attribute must be used with
+  extreme caution, because it can lead to deadlocks otherwise.
+
+* **`[Default]`**:
+  The `Default` attribute may be used to specify an enumerator value or union
+  field that will be used if an `Extensible` enumeration or union does not
+  deserialize to a known value on the receiver side, i.e. the sender is using a
+  newer version of the enum or union. This allows unknown values to be mapped to
+  a well-defined value that can be appropriately handled.
+
+  Note: The `Default` field for a union must be of nullable or integral type.
+  When a union is defaulted to this field, the field takes on the default value
+  for its type: null for nullable types, and zero/false for integral types.
+
+* **`[Extensible]`**:
+  The `Extensible` attribute may be specified for any enum or union definition.
+  For enums, this essentially disables builtin range validation when receiving
+  values of the enum type in a message, allowing older bindings to tolerate
+  unrecognized values from newer versions of the enum.
+
+  If an enum value within an extensible enum definition is affixed with the
+  `Default` attribute, out-of-range values for the enum will deserialize to that
+  default value. Only one enum value may be designated as the `Default`.
+
+  Similarly, a union marked `Extensible` will deserialize to its `Default` field
+  when an unrecognized field is received. Extensible unions MUST specify exactly
+  one `Default` field, and the field must be of nullable or integral type. When
+  defaulted to this field, the value is always null/zero/false as appropriate.
+
+  An `Extensible` enumeration REQUIRES that a `Default` value be specified,
+  so all new extensible enums should specify one.
+
+* **`[Native]`**:
+  The `Native` attribute may be specified for an empty struct declaration to
+  provide a nominal bridge between Mojo IPC and legacy `IPC::ParamTraits` or
+  `IPC_STRUCT_TRAITS*` macros. See [Repurposing Legacy IPC
+  Traits](/docs/mojo_ipc_conversion.md#repurposing-and-invocations) for more
+  details. Note support for this attribute is strictly limited to C++ bindings
+  generation.
+
+* **`[MinVersion=N]`**:
+  The `MinVersion` attribute is used to specify the version at which a given
+  field, enum value, interface method, or method parameter was introduced.
+  See [Versioning](#Versioning) for more details. `MinVersion` does not apply
+  to interfaces, structs or enums, but to the fields of those types.
+  `MinVersion` is not a module-global value, but it is ok to pretend it is by
+  skipping versions when adding fields or parameters.
+
+* **`[Stable]`**:
+  The `Stable` attribute specifies that a given mojom type or interface
+  definition can be considered stable over time, meaning it is safe to use for
+  things like persistent storage or communication between independent
+  version-skewed binaries. Stable definitions may only depend on builtin mojom
+  types or other stable definitions, and changes to such definitions MUST
+  preserve backward-compatibility through appropriate use of versioning.
+  Backward-compatibility of changes is enforced in the Chromium tree using a
+  strict presubmit check. See [Versioning](#Versioning) for more details on
+  backward-compatibility constraints.
+
+* **`[Uuid=<UUID>]`**:
+  Specifies a UUID to be associated with a given interface. The UUID is intended
+  to remain stable across all changes to the interface definition, including
+  name changes. The value given for this attribute should be a standard UUID
+  string representation as specified by RFC 4122. New UUIDs can be generated
+  with common tools such as `uuidgen`.
+
+* **`[RuntimeFeature=feature]`**
+  The `RuntimeFeature` attribute should reference a mojo `feature`. If this
+  feature is enabled (e.g. using `--enable-features={feature.name}`) then the
+  interface behaves entirely as expected. If the feature is not enabled the
+  interface cannot be bound to a concrete receiver or remote - attempting to do
+  so will result in the receiver or remote being reset() to an unbound state.
+  Note that this is a different concept to the build-time `EnableIf` directive.
+  `RuntimeFeature` is currently only supported for C++ bindings and has no
+  effect for, say, Java or TypeScript bindings (see https://crbug.com/1278253).
+
+* **`[EnableIf=value]`**:
+  The `EnableIf` attribute is used to conditionally enable definitions when the
+  mojom is parsed. If the `mojom` target in the GN file does not include the
+  matching `value` in the list of `enabled_features`, the definition will be
+  disabled. This is useful for mojom definitions that only make sense on one
+  platform. Note that the `EnableIf` attribute can only be set once per
+  definition and cannot be set at the same time as `EnableIfNot`. Also be aware
+  that only one condition can be tested, `EnableIf=value,xyz` introduces a new
+  `xyz` attribute. `xyz` is not part of the `EnableIf` condition that depends
+  only on the feature `value`. Complex conditions can be introduced via
+  enabled_features in `build.gn` files.
+
+* **`[EnableIfNot=value]`**:
+  The `EnableIfNot` attribute is used to conditionally enable definitions when
+  the mojom is parsed. If the `mojom` target in the GN file includes the
+  matching `value` in the list of `enabled_features`, the definition will be
+  disabled. This is useful for mojom definitions that only make sense on all but
+  one platform. Note that the `EnableIfNot` attribute can only be set once per
+  definition and cannot be set at the same time as `EnableIf`.
+
+* **`[ServiceSandbox=value]`**:
+  The `ServiceSandbox` attribute is used in Chromium to tag which sandbox a
+  service hosting an implementation of interface will be launched in. This only
+  applies to `C++` bindings. `value` should match a constant defined in an
+  imported `sandbox.mojom.Sandbox` enum (for Chromium this is
+  `//sandbox/policy/mojom/sandbox.mojom`), such as `kService`.
+
+* **`[RequireContext=enum]`**:
+  The `RequireContext` attribute is used in Chromium to tag interfaces that
+  should be passed (as remotes or receivers) only to privileged process
+  contexts. The process context must be an enum that is imported into the
+  mojom that defines the tagged interface. `RequireContext` may be used in
+  future to DCHECK or CHECK if remotes are made available in contexts that
+  conflict with the one provided in the interface definition. Process contexts
+  are not the same as the sandbox a process is running in, but will reflect
+  the set of capabilities provided to the service.
+
+* **`[AllowedContext=enum]`**:
+  The `AllowedContext` attribute is used in Chromium to tag methods that pass
+  remotes or receivers of interfaces that are marked with a `RequireContext`
+  attribute. The enum provided on the method must be equal or better (lower
+  numerically) than the one required on the interface being passed. At present
+  failing to specify an adequate `AllowedContext` value will cause mojom
+  generation to fail at compile time. In future DCHECKs or CHECKs might be
+  added to enforce that method is only called from a process context that meets
+  the given `AllowedContext` value. The enum must of the same type as that
+  specified in the interface's `RequireContext` attribute. Adding an
+  `AllowedContext` attribute to a method is a strong indication that you need
+   a detailed security review of your design - please reach out to the security
+   team.
+
+* **`[SupportsUrgent]`**:
+  The `SupportsUrgent` attribute is used in conjunction with
+  `mojo::UrgentMessageScope` in Chromium to tag messages as having high
+  priority. The IPC layer notifies the underlying scheduler upon both receiving
+  and processing an urgent message. At present, this attribute only affects
+  channel associated messages in the renderer process.
+
+## Generated Code For Target Languages
+
+When the bindings generator successfully processes an input Mojom file, it emits
+corresponding code for each supported target language. For more details on how
+Mojom concepts translate to a given target language, please refer to the
+bindings API documentation for that language:
+
+* [C++ Bindings](/mojo/public/cpp/bindings/README.md)
+* [JavaScript Bindings](/mojo/public/js/README.md)
+* [Java Bindings](/mojo/public/java/bindings/README.md)
+
+## Message Validation
+
+Regardless of target language, all interface messages are validated during
+deserialization before they are dispatched to a receiving implementation of the
+interface. This helps to ensure consistent validation across interfaces without
+leaving the burden to developers and security reviewers every time a new message
+is added.
+
+If a message fails validation, it is never dispatched. Instead a **connection
+error** is raised on the binding object (see
+[C++ Connection Errors](/mojo/public/cpp/bindings/README.md#Connection-Errors),
+[Java Connection Errors](/mojo/public/java/bindings/README.md#Connection-Errors),
+or
+[JavaScript Connection Errors](/mojo/public/js/README.md#Connection-Errors) for
+details.)
+
+Some baseline level of validation is done automatically for primitive Mojom
+types.
+
+### Non-Nullable Objects
+
+Mojom fields or parameter values (*e.g.*, structs, interfaces, arrays, *etc.*)
+may be marked nullable in Mojom definitions (see
+[Primitive Types](#Primitive-Types).) If a field or parameter is **not** marked
+nullable but a message is received with a null value in its place, that message
+will fail validation.
+
+### Enums
+
+Enums declared in Mojom are automatically validated against the range of legal
+values. For example if a Mojom declares the enum:
+
+``` cpp
+enum AdvancedBoolean {
+  kTrue = 0,
+  kFalse = 1,
+  kFileNotFound = 2,
+};
+```
+
+and a message is received with the integral value 3 (or anything other than 0,
+1, or 2) in place of some `AdvancedBoolean` field or parameter, the message will
+fail validation.
+
+*** note
+NOTE: It's possible to avoid this type of validation error by explicitly marking
+an enum as [Extensible](#Attributes) if you anticipate your enum being exchanged
+between two different versions of the binding interface. See
+[Versioning](#Versioning).
+***
+
+### Other failures
+
+There are a  host of internal validation errors that may occur when a malformed
+message is received, but developers should not be concerned with these
+specifically; in general they can only result from internal bindings bugs,
+compromised processes, or some remote endpoint making a dubious effort to
+manually encode their own bindings messages.
+
+### Custom Validation
+
+It's also possible for developers to define custom validation logic for specific
+Mojom struct types by exploiting the
+[type mapping](/mojo/public/cpp/bindings/README.md#Type-Mapping) system for C++
+bindings. Messages rejected by custom validation logic trigger the same
+validation failure behavior as the built-in type validation routines.
+
+## Associated Interfaces
+
+As mentioned in the [Primitive Types](#Primitive-Types) section above, pending_remote
+and pending_receiver fields and parameters may be marked as `associated`. This
+essentially means that they are piggy-backed on some other interface's message
+pipe.
+
+Because individual interface message pipes operate independently there can be no
+relative ordering guarantees among them. Associated interfaces are useful when
+one interface needs to guarantee strict FIFO ordering with respect to one or
+more other interfaces, as they allow interfaces to share a single pipe.
+
+Currently associated interfaces are only supported in generated C++ bindings.
+See the documentation for
+[C++ Associated Interfaces](/mojo/public/cpp/bindings/README.md#Associated-Interfaces).
+
+## Versioning
+
+### Overview
+
+*** note
+**NOTE:** You don't need to worry about versioning if you don't care about
+backwards compatibility. Today, all parts of the Chrome browser are
+updated atomically and there is not yet any possibility of any two
+Chrome processes communicating with two different versions of any given Mojom
+interface. On Chrome OS, there are several places where versioning is required.
+For example,
+[ARC++](https://developer.android.com/chrome-os/intro)
+uses versioned mojo to send IPC to the Android container.
+Likewise, the
+[Lacros](/docs/lacros.md)
+browser uses versioned mojo to talk to the ash system UI.
+***
+
+Services extend their interfaces to support new features over time, and clients
+want to use those new features when they are available. If services and clients
+are not updated at the same time, it's important for them to be able to
+communicate with each other using different snapshots (versions) of their
+interfaces.
+
+This document shows how to extend Mojom interfaces in a backwards-compatible
+way. Changing interfaces in a non-backwards-compatible way is not discussed,
+because in that case communication between different interface versions is
+impossible anyway.
+
+### Versioned Structs
+
+You can use the `MinVersion` [attribute](#Attributes) to indicate from which
+version a struct field is introduced. Assume you have the following struct:
+
+``` cpp
+struct Employee {
+  uint64 employee_id;
+  string name;
+};
+```
+
+and you would like to add birthday and nickname fields. You can add them as
+optional types with a `MinVersion` like so:
+
+``` cpp
+struct Employee {
+  uint64 employee_id;
+  string name;
+  [MinVersion=1] Date? birthday;
+  [MinVersion=1] string? nickname;
+};
+```
+
+*** note
+**NOTE:** Mojo object or handle types added with a `MinVersion` **MUST** be
+optional (nullable) or primitive. See [Primitive Types](#Primitive-Types) for
+details on nullable values.
+***
+
+By default, fields belong to version 0. New fields must be appended to the
+struct definition (*i.e*., existing fields must not change **ordinal value**)
+with the `MinVersion` attribute set to a number greater than any previous
+existing versions.
+
+The value of `MinVersion` is unrelated to ordinals. The choice of a particular
+version number is arbitrary. All its usage means is that a field isn't present
+before the numbered version.
+
+*** note
+**NOTE:** do not change existing fields in versioned structs, as this is
+not backwards-compatible. Instead, rename the old field to make its
+deprecation clear and add a new field with a new `MinVersion` number.
+***
+
+**Ordinal value** refers to the relative positional layout of a struct's fields
+(and an interface's methods) when encoded in a message. Implicitly, ordinal
+numbers are assigned to fields according to lexical position. In the example
+above, `employee_id` has an ordinal value of 0 and `name` has an ordinal value
+of 1.
+
+Ordinal values can be specified explicitly using `**@**` notation, subject to
+the following hard constraints:
+
+* For any given struct or interface, if any field or method explicitly specifies
+    an ordinal value, all fields or methods must explicitly specify an ordinal
+    value.
+* For an *N*-field struct, the set of explicitly assigned ordinal values must be
+    limited to the range *[0, N-1]*. Structs should include placeholder fields
+    to fill the ordinal positions of removed fields (for example "Unused_Field"
+    or "RemovedField", etc).
+
+You may reorder fields, but you must ensure that the ordinal values of existing
+fields remain unchanged. For example, the following struct remains
+backwards-compatible:
+
+``` cpp
+struct Employee {
+  uint64 employee_id@0;
+  [MinVersion=1] Date? birthday@2;
+  string name@1;
+  [MinVersion=1] string? nickname@3;
+};
+```
+
+### Versioned Interfaces
+
+There are two dimensions on which an interface can be extended
+
+**Appending New Parameters To Existing Methods**
+:   Parameter lists are treated as structs internally, so all the rules of
+    versioned structs apply to method parameter lists. The only difference is
+    that the version number is scoped to the whole interface rather than to any
+    individual parameter list.
+
+``` cpp
+// Old version:
+interface HumanResourceDatabase {
+  QueryEmployee(uint64 id) => (Employee? employee);
+};
+
+// New version:
+interface HumanResourceDatabase {
+  QueryEmployee(uint64 id, [MinVersion=1] bool retrieve_finger_print)
+      => (Employee? employee,
+          [MinVersion=1] array<uint8>? finger_print);
+};
+```
+
+Similar to [versioned structs](#Versioned-Structs), when you pass the parameter
+list of a request or response method to a destination using an older version of
+an interface, unrecognized fields are silently discarded.
+
+    Please note that adding a response to a message which did not previously
+    expect a response is a not a backwards-compatible change.
+
+**Appending New Methods**
+:   Similarly, you can reorder methods with explicit ordinal values as long as
+    the ordinal values of existing methods are unchanged.
+
+For example:
+
+``` cpp
+// Old version:
+interface HumanResourceDatabase {
+  QueryEmployee(uint64 id) => (Employee? employee);
+};
+
+// New version:
+interface HumanResourceDatabase {
+  QueryEmployee(uint64 id) => (Employee? employee);
+
+  [MinVersion=1]
+  AttachFingerPrint(uint64 id, array<uint8> finger_print)
+      => (bool success);
+};
+```
+
+If a method call is not recognized, it is considered a validation error and the
+receiver will close its end of the interface pipe. For example, if a client on
+version 1 of the above interface sends an `AttachFingerPrint` request to an
+implementation of version 0, the client will be disconnected.
+
+Bindings target languages that support versioning expose means to query or
+assert the remote version from a client handle (*e.g.*, an
+`mojo::Remote<T>` in C++ bindings.)
+
+See
+[C++ Versioning Considerations](/mojo/public/cpp/bindings/README.md#Versioning-Considerations)
+and
+[Java Versioning Considerations](/mojo/public/java/bindings/README.md#Versioning-Considerations)
+
+### Versioned Enums
+
+**By default, enums are non-extensible**, which means that generated message
+validation code does not expect to see new values in the future. When an unknown
+value is seen for a non-extensible enum field or parameter, a validation error
+is raised.
+
+If you want an enum to be extensible in the future, you can apply the
+`[Extensible]` [attribute](#Attributes):
+
+``` cpp
+[Extensible]
+enum Department {
+  kSales,
+  kDev,
+};
+```
+
+And later you can extend this enum without breaking backwards compatibility:
+
+``` cpp
+[Extensible]
+enum Department {
+  kSales,
+  kDev,
+  [MinVersion=1] kResearch,
+};
+```
+
+*** note
+**NOTE:** For versioned enum definitions, the use of a `[MinVersion]` attribute
+is strictly for documentation purposes. It has no impact on the generated code.
+***
+
+With extensible enums, bound interface implementations may receive unknown enum
+values and will need to deal with them gracefully. See
+[C++ Versioning Considerations](/mojo/public/cpp/bindings/README.md#Versioning-Considerations)
+for details.
+
+### Renaming versioned structs
+It's possible to rename versioned structs by using the `[RenamedFrom]` attribute.
+RenamedFrom
+
+``` cpp
+module asdf.mojom;
+
+// Old version:
+[Stable]
+struct OldStruct {
+};
+
+// New version:
+[Stable, RenamedFrom="asdf.mojom.OldStruct"]
+struct NewStruct {
+};
+```
+
+## Component targets
+
+If there are multiple components depending on the same mojom target within one binary,
+the target will need to be defined as `mojom_component` instead of `mojom`.
+Since `mojom` targets are generated `source_set` targets and `mojom_component` targets
+are generated `component` targets, you would use `mojom_component` in the same cases
+where you would use `component` for non-mojom files.
+*** note
+**NOTE**: by default, components for both blink and non-blink bindings are generated.
+Use the `disable_variants` target parameter to generate only non-blink bindings.
+You can also generate a `source_set` for one of the variants by defining
+[export_*](https://source.chromium.org/chromium/chromium/src/+/main:mojo/public/tools/bindings/mojom.gni;drc=739b9fbce50310c1dd2b59c279cd90a9319cb6e8;l=318)
+parameters for the `mojom_component` target.
+***
+
+## Grammar Reference
+
+Below is the (BNF-ish) context-free grammar of the Mojom language:
+
+```
+MojomFile = StatementList
+StatementList = Statement StatementList | Statement
+Statement = ModuleStatement | ImportStatement | Definition
+
+ModuleStatement = AttributeSection "module" Identifier ";"
+ImportStatement = "import" StringLiteral ";"
+Definition = Struct Union Interface Enum Feature Const
+
+AttributeSection = <empty> | "[" AttributeList "]"
+AttributeList = <empty> | NonEmptyAttributeList
+NonEmptyAttributeList = Attribute
+                      | Attribute "," NonEmptyAttributeList
+Attribute = Name
+          | Name "=" Name
+          | Name "=" Literal
+
+Struct = AttributeSection "struct" Name "{" StructBody "}" ";"
+       | AttributeSection "struct" Name ";"
+StructBody = <empty>
+           | StructBody Const
+           | StructBody Enum
+           | StructBody StructField
+StructField = AttributeSection TypeSpec Name Ordinal Default ";"
+
+Union = AttributeSection "union" Name "{" UnionBody "}" ";"
+UnionBody = <empty> | UnionBody UnionField
+UnionField = AttributeSection TypeSpec Name Ordinal ";"
+
+Interface = AttributeSection "interface" Name "{" InterfaceBody "}" ";"
+InterfaceBody = <empty>
+              | InterfaceBody Const
+              | InterfaceBody Enum
+              | InterfaceBody Method
+Method = AttributeSection Name Ordinal "(" ParameterList ")" Response ";"
+ParameterList = <empty> | NonEmptyParameterList
+NonEmptyParameterList = Parameter
+                      | Parameter "," NonEmptyParameterList
+Parameter = AttributeSection TypeSpec Name Ordinal
+Response = <empty> | "=>" "(" ParameterList ")"
+
+TypeSpec = TypeName "?" | TypeName
+TypeName = BasicTypeName
+         | Array
+         | FixedArray
+         | Map
+         | InterfaceRequest
+BasicTypeName = Identifier | "associated" Identifier | HandleType | NumericType
+NumericType = "bool" | "int8" | "uint8" | "int16" | "uint16" | "int32"
+            | "uint32" | "int64" | "uint64" | "float" | "double"
+HandleType = "handle" | "handle" "<" SpecificHandleType ">"
+SpecificHandleType = "message_pipe"
+                   | "shared_buffer"
+                   | "data_pipe_consumer"
+                   | "data_pipe_producer"
+                   | "platform"
+Array = "array" "<" TypeSpec ">"
+FixedArray = "array" "<" TypeSpec "," IntConstDec ">"
+Map = "map" "<" Identifier "," TypeSpec ">"
+InterfaceRequest = Identifier "&" | "associated" Identifier "&"
+
+Ordinal = <empty> | OrdinalValue
+
+Default = <empty> | "=" Constant
+
+Enum = AttributeSection "enum" Name "{" NonEmptyEnumValueList "}" ";"
+     | AttributeSection "enum" Name "{" NonEmptyEnumValueList "," "}" ";"
+NonEmptyEnumValueList = EnumValue | NonEmptyEnumValueList "," EnumValue
+EnumValue = AttributeSection Name
+          | AttributeSection Name "=" Integer
+          | AttributeSection Name "=" Identifier
+
+; Note: `feature` is a weak keyword and can appear as, say, a struct field name.
+Feature = AttributeSection "feature" Name "{" FeatureBody "}" ";"
+       | AttributeSection "feature" Name ";"
+FeatureBody = <empty>
+           | FeatureBody FeatureField
+FeatureField = AttributeSection TypeSpec Name Default ";"
+
+Const = "const" TypeSpec Name "=" Constant ";"
+
+Constant = Literal | Identifier ";"
+
+Identifier = Name | Name "." Identifier
+
+Literal = Integer | Float | "true" | "false" | "default" | StringLiteral
+
+Integer = IntConst | "+" IntConst | "-" IntConst
+IntConst = IntConstDec | IntConstHex
+
+Float = FloatConst | "+" FloatConst | "-" FloatConst
+
+; The rules below are for tokens matched strictly according to the given regexes
+
+Identifier = /[a-zA-Z_][0-9a-zA-Z_]*/
+IntConstDec = /0|(1-9[0-9]*)/
+IntConstHex = /0[xX][0-9a-fA-F]+/
+OrdinalValue = /@(0|(1-9[0-9]*))/
+FloatConst = ... # Imagine it's close enough to C-style float syntax.
+StringLiteral = ... # Imagine it's close enough to C-style string literals, including escapes.
+```
+
+## Additional Documentation
+
+[Mojom Message Format](https://docs.google.com/document/d/13pv9cFh5YKuBggDBQ1-AL8VReF-IYpFOFpRfvWFrwio/edit)
+:    Describes the wire format used by Mojo bindings interfaces over message
+     pipes.
+
+[Input Format of Mojom Message Validation Tests](https://docs.google.com/document/d/1-y-2IYctyX2NPaLxJjpJfzVNWCC2SR2MJAD9MpIytHQ/edit)
+:    Describes a text format used to facilitate bindings message validation
+     tests.
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/__init__.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/__init__.py
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check.py
new file mode 100644
index 00000000..e6e4f2c9
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check.py
@@ -0,0 +1,170 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Validate mojo attributes are allowed in Chrome before generation."""
+
+import mojom.generate.check as check
+import mojom.generate.module as module
+
+_COMMON_ATTRIBUTES = {
+    'EnableIf',
+    'EnableIfNot',
+}
+
+# For struct, union & parameter lists.
+_COMMON_FIELD_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'MinVersion',
+    'RenamedFrom',
+}
+
+# Note: `Default`` goes on the default _value_, not on the enum.
+# Note: [Stable] without [Extensible] is not allowed.
+_ENUM_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'Extensible',
+    'Native',
+    'Stable',
+    'RenamedFrom',
+    'Uuid',
+}
+
+# TODO(crbug.com/1234883) MinVersion is not needed for EnumVal.
+_ENUMVAL_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'Default',
+    'MinVersion',
+}
+
+_INTERFACE_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'RenamedFrom',
+    'RequireContext',
+    'RuntimeFeature',
+    'ServiceSandbox',
+    'Stable',
+    'Uuid',
+}
+
+_METHOD_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'AllowedContext',
+    'MinVersion',
+    'NoInterrupt',
+    'RuntimeFeature',
+    'SupportsUrgent',
+    'Sync',
+    'UnlimitedSize',
+}
+
+_MODULE_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'JavaConstantsClassName',
+    'JavaPackage',
+}
+
+_PARAMETER_ATTRIBUTES = _COMMON_FIELD_ATTRIBUTES
+
+_STRUCT_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'CustomSerializer',
+    'JavaClassName',
+    'Native',
+    'Stable',
+    'RenamedFrom',
+    'Uuid',
+}
+
+_STRUCT_FIELD_ATTRIBUTES = _COMMON_FIELD_ATTRIBUTES
+
+_UNION_ATTRIBUTES = _COMMON_ATTRIBUTES | {
+    'Extensible',
+    'Stable',
+    'RenamedFrom',
+    'Uuid',
+}
+
+_UNION_FIELD_ATTRIBUTES = _COMMON_FIELD_ATTRIBUTES | {
+    'Default',
+}
+
+# TODO(https://crbug.com/1193875) empty this set and remove the allowlist.
+_STABLE_ONLY_ALLOWLISTED_ENUMS = {
+    'crosapi.mojom.OptionalBool',
+    'crosapi.mojom.TriState',
+}
+
+
+class Check(check.Check):
+  def __init__(self, *args, **kwargs):
+    super(Check, self).__init__(*args, **kwargs)
+
+  def _Respell(self, allowed, attribute):
+    for a in allowed:
+      if a.lower() == attribute.lower():
+        return f" - Did you mean: {a}?"
+    return ""
+
+  def _CheckAttributes(self, context, allowed, attributes):
+    if not attributes:
+      return
+    for attribute in attributes:
+      if not attribute in allowed:
+        # Is there a close misspelling?
+        hint = self._Respell(allowed, attribute)
+        raise check.CheckException(
+            self.module,
+            f"attribute {attribute} not allowed on {context}{hint}")
+
+  def _CheckEnumAttributes(self, enum):
+    if enum.attributes:
+      self._CheckAttributes("enum", _ENUM_ATTRIBUTES, enum.attributes)
+      if 'Stable' in enum.attributes and not 'Extensible' in enum.attributes:
+        full_name = f"{self.module.mojom_namespace}.{enum.mojom_name}"
+        if full_name not in _STABLE_ONLY_ALLOWLISTED_ENUMS:
+          raise check.CheckException(
+              self.module,
+              f"[Extensible] required on [Stable] enum {full_name}")
+    for enumval in enum.fields:
+      self._CheckAttributes("enum value", _ENUMVAL_ATTRIBUTES,
+                            enumval.attributes)
+
+  def _CheckInterfaceAttributes(self, interface):
+    self._CheckAttributes("interface", _INTERFACE_ATTRIBUTES,
+                          interface.attributes)
+    for method in interface.methods:
+      self._CheckAttributes("method", _METHOD_ATTRIBUTES, method.attributes)
+      for param in method.parameters:
+        self._CheckAttributes("parameter", _PARAMETER_ATTRIBUTES,
+                              param.attributes)
+      if method.response_parameters:
+        for param in method.response_parameters:
+          self._CheckAttributes("parameter", _PARAMETER_ATTRIBUTES,
+                                param.attributes)
+    for enum in interface.enums:
+      self._CheckEnumAttributes(enum)
+
+  def _CheckModuleAttributes(self):
+    self._CheckAttributes("module", _MODULE_ATTRIBUTES, self.module.attributes)
+
+  def _CheckStructAttributes(self, struct):
+    self._CheckAttributes("struct", _STRUCT_ATTRIBUTES, struct.attributes)
+    for field in struct.fields:
+      self._CheckAttributes("struct field", _STRUCT_FIELD_ATTRIBUTES,
+                            field.attributes)
+    for enum in struct.enums:
+      self._CheckEnumAttributes(enum)
+
+  def _CheckUnionAttributes(self, union):
+    self._CheckAttributes("union", _UNION_ATTRIBUTES, union.attributes)
+    for field in union.fields:
+      self._CheckAttributes("union field", _UNION_FIELD_ATTRIBUTES,
+                            field.attributes)
+
+  def CheckModule(self):
+    """Note that duplicate attributes are forbidden at the parse phase.
+    We also do not need to look at the types of any parameters, as they will be
+    checked where they are defined. Consts do not have attributes so can be
+    skipped."""
+    self._CheckModuleAttributes()
+    for interface in self.module.interfaces:
+      self._CheckInterfaceAttributes(interface)
+    for enum in self.module.enums:
+      self._CheckEnumAttributes(enum)
+    for struct in self.module.structs:
+      self._CheckStructAttributes(struct)
+    for union in self.module.unions:
+      self._CheckUnionAttributes(union)
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check_unittest.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check_unittest.py
new file mode 100644
index 00000000..f1a50a4a
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check_unittest.py
@@ -0,0 +1,194 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+import mojom.generate.check as check
+from mojom_bindings_generator import LoadChecks, _Generate
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class FakeArgs:
+  """Fakes args to _Generate - intention is to do just enough to run checks"""
+
+  def __init__(self, tester, files=None):
+    """ `tester` is MojomParserTestCase for paths.
+        `files` will have tester path added."""
+    self.checks_string = 'attributes'
+    self.depth = tester.GetPath('')
+    self.filelist = None
+    self.filename = [tester.GetPath(x) for x in files]
+    self.gen_directories = tester.GetPath('gen')
+    self.generators_string = ''
+    self.import_directories = []
+    self.output_dir = tester.GetPath('out')
+    self.scrambled_message_id_salt_paths = None
+    self.typemaps = []
+    self.variant = 'none'
+
+
+class MojoBindingsCheckTest(MojomParserTestCase):
+  def _ParseAndGenerate(self, mojoms):
+    self.ParseMojoms(mojoms)
+    args = FakeArgs(self, files=mojoms)
+    _Generate(args, {})
+
+  def _testValid(self, filename, content):
+    self.WriteFile(filename, content)
+    self._ParseAndGenerate([filename])
+
+  def _testThrows(self, filename, content, regexp):
+    mojoms = []
+    self.WriteFile(filename, content)
+    mojoms.append(filename)
+    with self.assertRaisesRegexp(check.CheckException, regexp):
+      self._ParseAndGenerate(mojoms)
+
+  def testLoads(self):
+    """Validate that the check is registered under the expected name."""
+    check_modules = LoadChecks('attributes')
+    self.assertTrue(check_modules['attributes'])
+
+  def testNoAnnotations(self):
+    # Undecorated mojom should be fine.
+    self._testValid(
+        "a.mojom", """
+      module a;
+      struct Bar { int32 a; };
+      enum Hello { kValue };
+      union Thingy { Bar b; Hello hi; };
+      interface Foo {
+        Foo(int32 a, Hello hi, Thingy t) => (Bar b);
+      };
+    """)
+
+  def testValidAnnotations(self):
+    # Obviously this is meaningless and won't generate, but it should pass
+    # the attribute check's validation.
+    self._testValid(
+        "a.mojom", """
+      [JavaConstantsClassName="FakeClass",JavaPackage="org.chromium.Fake"]
+      module a;
+      [Stable, Extensible]
+      enum Hello { [Default] kValue, kValue2, [MinVersion=2] kValue3 };
+      [Native]
+      enum NativeEnum {};
+      [Stable,Extensible]
+      union Thingy { Bar b; [Default]int32 c; Hello hi; };
+
+      [Stable,RenamedFrom="module.other.Foo",
+       Uuid="4C178401-4B07-4C2E-9255-5401A943D0C7"]
+      struct Structure { Hello hi; };
+
+      [ServiceSandbox=Hello.kValue,RequireContext=Hello.kValue,Stable,
+       Uuid="2F17D7DD-865A-4B1C-9394-9C94E035E82F"]
+      interface Foo {
+        [AllowedContext=Hello.kValue]
+        Foo@0(int32 a) => (int32 b);
+        [MinVersion=2,Sync,UnlimitedSize,NoInterrupt]
+        Bar@1(int32 b, [MinVersion=2]Structure? s) => (bool c);
+      };
+
+      [RuntimeFeature=test.mojom.FeatureName]
+      interface FooFeatureControlled {};
+
+      interface FooMethodFeatureControlled {
+        [RuntimeFeature=test.mojom.FeatureName]
+        MethodWithFeature() => (bool c);
+      };
+    """)
+
+  def testWrongModuleStable(self):
+    contents = """
+      // err: module cannot be Stable
+      [Stable]
+      module a;
+      enum Hello { kValue, kValue2, kValue3 };
+      enum NativeEnum {};
+      struct Structure { Hello hi; };
+
+      interface Foo {
+        Foo(int32 a) => (int32 b);
+        Bar(int32 b, Structure? s) => (bool c);
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'attribute Stable not allowed on module')
+
+  def testWrongEnumDefault(self):
+    contents = """
+      module a;
+      // err: default should go on EnumValue not Enum.
+      [Default=kValue]
+      enum Hello { kValue, kValue2, kValue3 };
+      enum NativeEnum {};
+      struct Structure { Hello hi; };
+
+      interface Foo {
+        Foo(int32 a) => (int32 b);
+        Bar(int32 b, Structure? s) => (bool c);
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'attribute Default not allowed on enum')
+
+  def testWrongStructMinVersion(self):
+    contents = """
+      module a;
+      enum Hello { kValue, kValue2, kValue3 };
+      enum NativeEnum {};
+      // err: struct cannot have MinVersion.
+      [MinVersion=2]
+      struct Structure { Hello hi; };
+
+      interface Foo {
+        Foo(int32 a) => (int32 b);
+        Bar(int32 b, Structure? s) => (bool c);
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'attribute MinVersion not allowed on struct')
+
+  def testWrongMethodRequireContext(self):
+    contents = """
+      module a;
+      enum Hello { kValue, kValue2, kValue3 };
+      enum NativeEnum {};
+      struct Structure { Hello hi; };
+
+      interface Foo {
+        // err: RequireContext is for interfaces.
+        [RequireContext=Hello.kValue]
+        Foo(int32 a) => (int32 b);
+        Bar(int32 b, Structure? s) => (bool c);
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'RequireContext not allowed on method')
+
+  def testWrongMethodRequireContext(self):
+    # crbug.com/1230122
+    contents = """
+      module a;
+      interface Foo {
+        // err: sync not Sync.
+        [sync]
+        Foo(int32 a) => (int32 b);
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'attribute sync not allowed.*Did you mean: Sync')
+
+  def testStableExtensibleEnum(self):
+    # crbug.com/1193875
+    contents = """
+      module a;
+      [Stable]
+      enum Foo {
+        kDefaultVal,
+        kOtherVal = 2,
+      };
+    """
+    self._testThrows('a.mojom', contents,
+                     'Extensible.*?required.*?Stable.*?enum')
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_definitions_check.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_definitions_check.py
new file mode 100644
index 00000000..702d41c3
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_definitions_check.py
@@ -0,0 +1,34 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Ensure no duplicate type definitions before generation."""
+
+import mojom.generate.check as check
+import mojom.generate.module as module
+
+
+class Check(check.Check):
+  def __init__(self, *args, **kwargs):
+    super(Check, self).__init__(*args, **kwargs)
+
+  def CheckModule(self):
+    kinds = dict()
+    for module in self.module.imports:
+      for kind in module.enums + module.structs + module.unions:
+        kind_name = f'{kind.module.mojom_namespace}.{kind.mojom_name}'
+        if kind_name in kinds:
+          previous_module = kinds[kind_name]
+          if previous_module.path != module.path:
+            raise check.CheckException(
+                self.module, f"multiple-definition for type {kind_name}" +
+                f"(defined in both {previous_module} and {module})")
+        kinds[kind_name] = kind.module
+
+    for kind in self.module.enums + self.module.structs + self.module.unions:
+      kind_name = f'{kind.module.mojom_namespace}.{kind.mojom_name}'
+      if kind_name in kinds:
+        previous_module = kinds[kind_name]
+        raise check.CheckException(
+            self.module, f"multiple-definition for type {kind_name}" +
+            f"(previous definition in {previous_module})")
+    return True
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check.py
new file mode 100644
index 00000000..07f51a64
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check.py
@@ -0,0 +1,62 @@
+# Copyright 2023 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Validate mojo runtime feature guarded interfaces are nullable."""
+
+import mojom.generate.check as check
+import mojom.generate.module as module
+
+
+class Check(check.Check):
+  def __init__(self, *args, **kwargs):
+    super(Check, self).__init__(*args, **kwargs)
+
+  # `param` is an Interface of some sort.
+  def _CheckNonNullableFeatureGuardedInterface(self, kind):
+    # Only need to validate interface if it has a RuntimeFeature
+    if not kind.kind.runtime_feature:
+      return
+    # Nullable (optional) is ok as the interface expects they might not be sent.
+    if kind.is_nullable:
+      return
+    interface = kind.kind.mojom_name
+    raise check.CheckException(
+        self.module,
+        f"interface {interface} has a RuntimeFeature but is not nullable")
+
+  # `param` can be a lot of things so check if it is a remote/receiver.
+  # Array/Map must be recursed into.
+  def _CheckFieldOrParam(self, kind):
+    if module.IsAnyInterfaceKind(kind):
+      self._CheckNonNullableFeatureGuardedInterface(kind)
+    if module.IsArrayKind(kind):
+      self._CheckFieldOrParam(kind.kind)
+    if module.IsMapKind(kind):
+      self._CheckFieldOrParam(kind.key_kind)
+      self._CheckFieldOrParam(kind.value_kind)
+
+  def _CheckInterfaceFeatures(self, interface):
+    for method in interface.methods:
+      for param in method.parameters:
+        self._CheckFieldOrParam(param.kind)
+      if method.response_parameters:
+        for param in method.response_parameters:
+          self._CheckFieldOrParam(param.kind)
+
+  def _CheckStructFeatures(self, struct):
+    for field in struct.fields:
+      self._CheckFieldOrParam(field.kind)
+
+  def _CheckUnionFeatures(self, union):
+    for field in union.fields:
+      self._CheckFieldOrParam(field.kind)
+
+  def CheckModule(self):
+    """Validate that any runtime feature guarded interfaces that might be passed
+    over mojo are nullable."""
+    for interface in self.module.interfaces:
+      self._CheckInterfaceFeatures(interface)
+    for struct in self.module.structs:
+      self._CheckStructFeatures(struct)
+    for union in self.module.unions:
+      self._CheckUnionFeatures(union)
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check_unittest.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check_unittest.py
new file mode 100644
index 00000000..e96152fd
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check_unittest.py
@@ -0,0 +1,173 @@
+# Copyright 2023 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+import mojom.generate.check as check
+from mojom_bindings_generator import LoadChecks, _Generate
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class FakeArgs:
+  """Fakes args to _Generate - intention is to do just enough to run checks"""
+  def __init__(self, tester, files=None):
+    """ `tester` is MojomParserTestCase for paths.
+        `files` will have tester path added."""
+    self.checks_string = 'features'
+    self.depth = tester.GetPath('')
+    self.filelist = None
+    self.filename = [tester.GetPath(x) for x in files]
+    self.gen_directories = tester.GetPath('gen')
+    self.generators_string = ''
+    self.import_directories = []
+    self.output_dir = tester.GetPath('out')
+    self.scrambled_message_id_salt_paths = None
+    self.typemaps = []
+    self.variant = 'none'
+
+
+class MojoBindingsCheckTest(MojomParserTestCase):
+  def _ParseAndGenerate(self, mojoms):
+    self.ParseMojoms(mojoms)
+    args = FakeArgs(self, files=mojoms)
+    _Generate(args, {})
+
+  def assertValid(self, filename, content):
+    self.WriteFile(filename, content)
+    self._ParseAndGenerate([filename])
+
+  def assertThrows(self, filename, content, regexp):
+    mojoms = []
+    self.WriteFile(filename, content)
+    mojoms.append(filename)
+    with self.assertRaisesRegexp(check.CheckException, regexp):
+      self._ParseAndGenerate(mojoms)
+
+  def testLoads(self):
+    """Validate that the check is registered under the expected name."""
+    check_modules = LoadChecks('features')
+    self.assertTrue(check_modules['features'])
+
+  def testNullableOk(self):
+    self.assertValid(
+        "a.mojom", """
+          module a;
+          // Scaffolding.
+          feature kFeature {
+            const string name = "Hello";
+            const bool enabled_state = false;
+          };
+          [RuntimeFeature=kFeature]
+          interface Guarded {
+          };
+
+          // Unguarded interfaces should be ok everywhere.
+          interface NotGuarded { };
+
+          // Optional (nullable) interfaces should be ok everywhere:
+          struct Bar {
+            pending_remote<Guarded>? remote;
+            pending_receiver<Guarded>? receiver;
+          };
+          union Thingy {
+            pending_remote<Guarded>? remote;
+            pending_receiver<Guarded>? receiver;
+          };
+          interface Foo {
+            Foo(
+              pending_remote<Guarded>? remote,
+              pending_receiver<Guarded>? receiver,
+              pending_associated_remote<Guarded>? a_remote,
+              pending_associated_receiver<Guarded>? a_receiver,
+              // Unguarded interfaces do not have to be nullable.
+              pending_remote<NotGuarded> remote,
+              pending_receiver<NotGuarded> receiver,
+              pending_associated_remote<NotGuarded> a_remote,
+              pending_associated_receiver<NotGuarded> a_receiver
+            ) => (
+              pending_remote<Guarded>? remote,
+              pending_receiver<Guarded>? receiver
+            );
+            Bar(array<pending_remote<Guarded>?> remote)
+              => (map<string, pending_receiver<Guarded>?> a);
+          };
+    """)
+
+  def testMethodParamsMustBeNullable(self):
+    prelude = """
+      module a;
+      // Scaffolding.
+      feature kFeature {
+        const string name = "Hello";
+        const bool enabled_state = false;
+      };
+      [RuntimeFeature=kFeature]
+      interface Guarded { };
+    """
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(pending_remote<Guarded> a) => ();
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(bool foo) => (pending_receiver<Guarded> a);
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(pending_receiver<Guarded> a) => ();
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(pending_associated_remote<Guarded> a) => ();
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(pending_associated_receiver<Guarded> a) => ();
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(array<pending_associated_receiver<Guarded>> a) => ();
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          interface Trial {
+            Method(map<string, pending_associated_receiver<Guarded>> a) => ();
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+
+  def testStructUnionMembersMustBeNullable(self):
+    prelude = """
+      module a;
+      // Scaffolding.
+      feature kFeature {
+        const string name = "Hello";
+        const bool enabled_state = false;
+      };
+      [RuntimeFeature=kFeature]
+      interface Guarded { };
+    """
+    self.assertThrows(
+        'a.mojom', prelude + """
+          struct Trial {
+            pending_remote<Guarded> a;
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
+    self.assertThrows(
+        'a.mojom', prelude + """
+          union Trial {
+            pending_remote<Guarded> a;
+          };
+                     """, 'interface Guarded has a RuntimeFeature')
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_check.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_check.py
new file mode 100644
index 00000000..d570e26c
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_check.py
@@ -0,0 +1,102 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Validate RequireContext and AllowedContext annotations before generation."""
+
+import mojom.generate.check as check
+import mojom.generate.module as module
+
+
+class Check(check.Check):
+  def __init__(self, *args, **kwargs):
+    self.kind_to_interfaces = dict()
+    super(Check, self).__init__(*args, **kwargs)
+
+  def _IsPassedInterface(self, candidate):
+    if isinstance(
+        candidate.kind,
+        (module.PendingReceiver, module.PendingRemote,
+         module.PendingAssociatedReceiver, module.PendingAssociatedRemote)):
+      return True
+    return False
+
+  def _CheckInterface(self, method, param):
+    # |param| is a pending_x<Interface> so need .kind.kind to get Interface.
+    interface = param.kind.kind
+    if interface.require_context:
+      if method.allowed_context is None:
+        raise check.CheckException(
+            self.module, "method `{}` has parameter `{}` which passes interface"
+            " `{}` that requires an AllowedContext annotation but none exists.".
+            format(
+                method.mojom_name,
+                param.mojom_name,
+                interface.mojom_name,
+            ))
+      # If a string was provided, or if an enum was not imported, this will
+      # be a string and we cannot validate that it is in range.
+      if not isinstance(method.allowed_context, module.EnumValue):
+        raise check.CheckException(
+            self.module,
+            "method `{}` has AllowedContext={} which is not a valid enum value."
+            .format(method.mojom_name, method.allowed_context))
+      # EnumValue must be from the same enum to be compared.
+      if interface.require_context.enum != method.allowed_context.enum:
+        raise check.CheckException(
+            self.module, "method `{}` has parameter `{}` which passes interface"
+            " `{}` that requires AllowedContext={} but one of kind `{}` was "
+            "provided.".format(
+                method.mojom_name,
+                param.mojom_name,
+                interface.mojom_name,
+                interface.require_context.enum,
+                method.allowed_context.enum,
+            ))
+      # RestrictContext enums have most privileged field first (lowest value).
+      interface_value = interface.require_context.field.numeric_value
+      method_value = method.allowed_context.field.numeric_value
+      if interface_value < method_value:
+        raise check.CheckException(
+            self.module, "RequireContext={} > AllowedContext={} for method "
+            "`{}` which passes interface `{}`.".format(
+                interface.require_context.GetSpec(),
+                method.allowed_context.GetSpec(), method.mojom_name,
+                interface.mojom_name))
+      return True
+
+  def _GatherReferencedInterfaces(self, field):
+    key = field.kind.spec
+    # structs/unions can nest themselves so we need to bookkeep.
+    if not key in self.kind_to_interfaces:
+      # Might reference ourselves so have to create the list first.
+      self.kind_to_interfaces[key] = set()
+      for param in field.kind.fields:
+        if self._IsPassedInterface(param):
+          self.kind_to_interfaces[key].add(param)
+        elif isinstance(param.kind, (module.Struct, module.Union)):
+          for iface in self._GatherReferencedInterfaces(param):
+            self.kind_to_interfaces[key].add(iface)
+    return self.kind_to_interfaces[key]
+
+  def _CheckParams(self, method, params):
+    # Note: we have to repeat _CheckParams for each method as each might have
+    # different AllowedContext= attributes. We cannot memoize this function,
+    # but can do so for gathering referenced interfaces as their RequireContext
+    # attributes do not change.
+    for param in params:
+      if self._IsPassedInterface(param):
+        self._CheckInterface(method, param)
+      elif isinstance(param.kind, (module.Struct, module.Union)):
+        for interface in self._GatherReferencedInterfaces(param):
+          self._CheckInterface(method, interface)
+
+  def _CheckMethod(self, method):
+    if method.parameters:
+      self._CheckParams(method, method.parameters)
+    if method.response_parameters:
+      self._CheckParams(method, method.response_parameters)
+
+  def CheckModule(self):
+    for interface in self.module.interfaces:
+      for method in interface.methods:
+        self._CheckMethod(method)
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_checks_unittest.py b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_checks_unittest.py
new file mode 100644
index 00000000..a6cd71e2
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_checks_unittest.py
@@ -0,0 +1,254 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+import mojom.generate.check as check
+from mojom_bindings_generator import LoadChecks, _Generate
+from mojom_parser_test_case import MojomParserTestCase
+
+# Mojoms that we will use in multiple tests.
+basic_mojoms = {
+    'level.mojom':
+    """
+  module level;
+  enum Level {
+    kHighest,
+    kMiddle,
+    kLowest,
+  };
+  """,
+    'interfaces.mojom':
+    """
+  module interfaces;
+  import "level.mojom";
+  struct Foo {int32 bar;};
+  [RequireContext=level.Level.kHighest]
+  interface High {
+    DoFoo(Foo foo);
+  };
+  [RequireContext=level.Level.kMiddle]
+  interface Mid {
+    DoFoo(Foo foo);
+  };
+  [RequireContext=level.Level.kLowest]
+  interface Low {
+    DoFoo(Foo foo);
+  };
+  """
+}
+
+
+class FakeArgs:
+  """Fakes args to _Generate - intention is to do just enough to run checks"""
+
+  def __init__(self, tester, files=None):
+    """ `tester` is MojomParserTestCase for paths.
+        `files` will have tester path added."""
+    self.checks_string = 'restrictions'
+    self.depth = tester.GetPath('')
+    self.filelist = None
+    self.filename = [tester.GetPath(x) for x in files]
+    self.gen_directories = tester.GetPath('gen')
+    self.generators_string = ''
+    self.import_directories = []
+    self.output_dir = tester.GetPath('out')
+    self.scrambled_message_id_salt_paths = None
+    self.typemaps = []
+    self.variant = 'none'
+
+
+class MojoBindingsCheckTest(MojomParserTestCase):
+  def _WriteBasicMojoms(self):
+    for filename, contents in basic_mojoms.items():
+      self.WriteFile(filename, contents)
+    return list(basic_mojoms.keys())
+
+  def _ParseAndGenerate(self, mojoms):
+    self.ParseMojoms(mojoms)
+    args = FakeArgs(self, files=mojoms)
+    _Generate(args, {})
+
+  def testLoads(self):
+    """Validate that the check is registered under the expected name."""
+    check_modules = LoadChecks('restrictions')
+    self.assertTrue(check_modules['restrictions'])
+
+  def testValidAnnotations(self):
+    mojoms = self._WriteBasicMojoms()
+
+    a = 'a.mojom'
+    self.WriteFile(
+        a, """
+      module a;
+      import "level.mojom";
+      import "interfaces.mojom";
+
+      interface PassesHigh {
+        [AllowedContext=level.Level.kHighest]
+        DoHigh(pending_receiver<interfaces.High> hi);
+      };
+      interface PassesMedium {
+        [AllowedContext=level.Level.kMiddle]
+        DoMedium(pending_receiver<interfaces.Mid> hi);
+        [AllowedContext=level.Level.kMiddle]
+        DoMediumRem(pending_remote<interfaces.Mid> hi);
+        [AllowedContext=level.Level.kMiddle]
+        DoMediumAssoc(pending_associated_receiver<interfaces.Mid> hi);
+        [AllowedContext=level.Level.kMiddle]
+        DoMediumAssocRem(pending_associated_remote<interfaces.Mid> hi);
+      };
+      interface PassesLow {
+        [AllowedContext=level.Level.kLowest]
+        DoLow(pending_receiver<interfaces.Low> hi);
+      };
+
+      struct One { pending_receiver<interfaces.High> hi; };
+      struct Two { One one; };
+      interface PassesNestedHigh {
+        [AllowedContext=level.Level.kHighest]
+        DoNestedHigh(Two two);
+      };
+
+      // Allowed as PassesHigh is not itself restricted.
+      interface PassesPassesHigh {
+        DoPass(pending_receiver<PassesHigh> hiho);
+      };
+    """)
+    mojoms.append(a)
+    self._ParseAndGenerate(mojoms)
+
+  def _testThrows(self, filename, content, regexp):
+    mojoms = self._WriteBasicMojoms()
+    self.WriteFile(filename, content)
+    mojoms.append(filename)
+    with self.assertRaisesRegexp(check.CheckException, regexp):
+      self._ParseAndGenerate(mojoms)
+
+  def testMissingAnnotation(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+
+      interface PassesHigh {
+        // err: missing annotation.
+        DoHigh(pending_receiver<interfaces.High> hi);
+      };
+    """
+    self._testThrows('b.mojom', contents, 'require.*?AllowedContext')
+
+  def testAllowTooLow(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+
+      interface PassesHigh {
+        // err: level is worse than required.
+        [AllowedContext=level.Level.kMiddle]
+        DoHigh(pending_receiver<interfaces.High> hi);
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'RequireContext=.*?kHighest > AllowedContext=.*?kMiddle')
+
+  def testWrongEnumInAllow(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+      enum Blah {
+        kZero,
+      };
+      interface PassesHigh {
+        // err: different enums.
+        [AllowedContext=Blah.kZero]
+        DoHigh(pending_receiver<interfaces.High> hi);
+      };
+    """
+    self._testThrows('b.mojom', contents, 'but one of kind')
+
+  def testNotAnEnumInAllow(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+      interface PassesHigh {
+        // err: not an enum.
+        [AllowedContext=doopdedoo.mojom.kWhatever]
+        DoHigh(pending_receiver<interfaces.High> hi);
+      };
+    """
+    self._testThrows('b.mojom', contents, 'not a valid enum value')
+
+  def testMissingAllowedForNestedStructs(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+      struct One { pending_receiver<interfaces.High> hi; };
+      struct Two { One one; };
+      interface PassesNestedHigh {
+        // err: missing annotation.
+        DoNestedHigh(Two two);
+      };
+    """
+    self._testThrows('b.mojom', contents, 'require.*?AllowedContext')
+
+  def testMissingAllowedForNestedUnions(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+      struct One { pending_receiver<interfaces.High> hi; };
+      struct Two { One one; };
+      union Three {One one; Two two; };
+      interface PassesNestedHigh {
+        // err: missing annotation.
+        DoNestedHigh(Three three);
+      };
+    """
+    self._testThrows('b.mojom', contents, 'require.*?AllowedContext')
+
+  def testMultipleInterfacesThrows(self):
+    contents = """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+      struct One { pending_receiver<interfaces.High> hi; };
+      interface PassesMultipleInterfaces {
+        [AllowedContext=level.Level.kMiddle]
+        DoMultiple(
+          pending_remote<interfaces.Mid> mid,
+          pending_receiver<interfaces.High> hi,
+          One one
+        );
+      };
+    """
+    self._testThrows('b.mojom', contents,
+                     'RequireContext=.*?kHighest > AllowedContext=.*?kMiddle')
+
+  def testMultipleInterfacesAllowed(self):
+    """Multiple interfaces can be passed, all satisfy the level."""
+    mojoms = self._WriteBasicMojoms()
+
+    b = "b.mojom"
+    self.WriteFile(
+        b, """
+      module b;
+      import "level.mojom";
+      import "interfaces.mojom";
+      struct One { pending_receiver<interfaces.High> hi; };
+      interface PassesMultipleInterfaces {
+        [AllowedContext=level.Level.kHighest]
+        DoMultiple(
+          pending_receiver<interfaces.High> hi,
+          pending_remote<interfaces.Mid> mid,
+          One one
+        );
+      };
+    """)
+    mojoms.append(b)
+    self._ParseAndGenerate(mojoms)
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/concatenate-files.py b/utils/codegen/ipc/mojo/public/tools/bindings/concatenate-files.py
new file mode 100755
index 00000000..4dd26d4a
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/concatenate-files.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+# Copyright 2019 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# This utility concatenates several files into one. On Unix-like systems
+# it is equivalent to:
+#   cat file1 file2 file3 ...files... > target
+#
+# The reason for writing a separate utility is that 'cat' is not available
+# on all supported build platforms, but Python is, and hence this provides
+# us with an easy and uniform way of doing this on all platforms.
+
+# for py2/py3 compatibility
+from __future__ import print_function
+
+import optparse
+import sys
+
+
+def Concatenate(filenames):
+  """Concatenate files.
+
+  Args:
+    files: Array of file names.
+           The last name is the target; all earlier ones are sources.
+
+  Returns:
+    True, if the operation was successful.
+  """
+  if len(filenames) < 2:
+    print("An error occurred generating %s:\nNothing to do." % filenames[-1])
+    return False
+
+  try:
+    with open(filenames[-1], "wb") as target:
+      for filename in filenames[:-1]:
+        with open(filename, "rb") as current:
+          target.write(current.read())
+    return True
+  except IOError as e:
+    print("An error occurred when writing %s:\n%s" % (filenames[-1], e))
+    return False
+
+
+def main():
+  parser = optparse.OptionParser()
+  parser.set_usage("""Concatenate several files into one.
+      Equivalent to: cat file1 ... > target.""")
+  (_options, args) = parser.parse_args()
+  sys.exit(0 if Concatenate(args) else 1)
+
+
+if __name__ == "__main__":
+  main()
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py b/utils/codegen/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py
new file mode 100755
index 00000000..7d56c9f9
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py
@@ -0,0 +1,75 @@
+#!/usr/bin/env python
+# Copyright 2018 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Simple utility which concatenates a set of files into a single output file
+while also stripping any goog.provide or goog.require lines. This allows us to
+provide a very primitive sort of "compilation" without any extra toolchain
+support and without having to modify otherwise compilable sources in the tree
+which use these directives.
+
+goog.provide lines are replaced with an equivalent invocation of
+mojo.internal.exportModule, which accomplishes essentially the same thing in an
+uncompiled context. A singular exception is made for the 'mojo.internal' export,
+which is instead replaced with an inlined assignment to initialize the
+namespace.
+"""
+
+from __future__ import print_function
+
+import optparse
+import re
+import sys
+
+
+_MOJO_INTERNAL_MODULE_NAME = "mojo.internal"
+_MOJO_EXPORT_MODULE_SYMBOL = "mojo.internal.exportModule"
+
+
+def FilterLine(filename, line, output):
+  if line.startswith("goog.require"):
+    return
+
+  if line.startswith("goog.provide"):
+    match = re.match(r"goog.provide\('([^']+)'\);", line)
+    if not match:
+      print("Invalid goog.provide line in %s:\n%s" % (filename, line))
+      sys.exit(1)
+
+    module_name = match.group(1)
+    if module_name == _MOJO_INTERNAL_MODULE_NAME:
+      output.write("self.mojo = { internal: {} };")
+    else:
+      output.write("%s('%s');\n" % (_MOJO_EXPORT_MODULE_SYMBOL, module_name))
+    return
+
+  output.write(line)
+
+def ConcatenateAndReplaceExports(filenames):
+  if (len(filenames) < 2):
+    print("At least two filenames (one input and the output) are required.")
+    return False
+
+  try:
+    with open(filenames[-1], "w") as target:
+      for filename in filenames[:-1]:
+        with open(filename, "r") as current:
+          for line in current.readlines():
+            FilterLine(filename, line, target)
+    return True
+  except IOError as e:
+    print("Error generating %s\n: %s" % (filenames[-1], e))
+    return False
+
+def main():
+  parser = optparse.OptionParser()
+  parser.set_usage("""file1 [file2...] outfile
+    Concatenate several files into one, stripping Closure provide and
+    require directives along the way.""")
+  (_, args) = parser.parse_args()
+  sys.exit(0 if ConcatenateAndReplaceExports(args) else 1)
+
+
+if __name__ == "__main__":
+  main()
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/gen_data_files_list.py b/utils/codegen/ipc/mojo/public/tools/bindings/gen_data_files_list.py
new file mode 100644
index 00000000..c6daff03
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/gen_data_files_list.py
@@ -0,0 +1,48 @@
+# Copyright 2017 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Generates a list of all files in a directory.
+
+This script takes in a directory and an output file name as input.
+It then reads the directory and creates a list of all file names
+in that directory.  The list is written to the output file.
+There is also an option to pass in '-p' or '--pattern'
+which will check each file name against a regular expression
+pattern that is passed in.  Only files which match the regex
+will be written to the list.
+"""
+
+from __future__ import print_function
+
+import os
+import re
+import sys
+
+from optparse import OptionParser
+
+sys.path.insert(
+    0,
+    os.path.join(
+        os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "mojom"))
+
+from mojom.generate.generator import WriteFile
+
+
+def main():
+  parser = OptionParser()
+  parser.add_option('-d', '--directory', help='Read files from DIRECTORY')
+  parser.add_option('-o', '--output', help='Write list to FILE')
+  parser.add_option('-p',
+                    '--pattern',
+                    help='Only reads files that name matches PATTERN',
+                    default=".")
+  (options, _) = parser.parse_args()
+  pattern = re.compile(options.pattern)
+  files = [f for f in os.listdir(options.directory) if pattern.match(f)]
+
+  contents = '\n'.join(f for f in files) + '\n'
+  WriteFile(contents, options.output)
+
+
+if __name__ == '__main__':
+  sys.exit(main())
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/generate_type_mappings.py b/utils/codegen/ipc/mojo/public/tools/bindings/generate_type_mappings.py
new file mode 100755
index 00000000..4a53e2bf
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/generate_type_mappings.py
@@ -0,0 +1,135 @@
+#!/usr/bin/env python
+# Copyright 2016 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Generates a JSON typemap from its command-line arguments and dependencies.
+
+Each typemap should be specified in an command-line argument of the form
+key=value, with an argument of "--start-typemap" preceding each typemap.
+
+For example,
+generate_type_mappings.py --output=foo.typemap --start-typemap \\
+    public_headers=foo.h traits_headers=foo_traits.h \\
+    type_mappings=mojom.Foo=FooImpl
+
+generates a foo.typemap containing
+{
+  "c++": {
+    "mojom.Foo": {
+      "typename": "FooImpl",
+      "traits_headers": [
+        "foo_traits.h"
+      ],
+      "public_headers": [
+        "foo.h"
+      ]
+    }
+  }
+}
+
+Then,
+generate_type_mappings.py --dependency foo.typemap --output=bar.typemap \\
+    --start-typemap public_headers=bar.h traits_headers=bar_traits.h \\
+    type_mappings=mojom.Bar=BarImpl
+
+generates a bar.typemap containing
+{
+  "c++": {
+    "mojom.Bar": {
+      "typename": "BarImpl",
+      "traits_headers": [
+        "bar_traits.h"
+      ],
+      "public_headers": [
+        "bar.h"
+      ]
+    },
+    "mojom.Foo": {
+      "typename": "FooImpl",
+      "traits_headers": [
+        "foo_traits.h"
+      ],
+      "public_headers": [
+        "foo.h"
+      ]
+    }
+  }
+}
+"""
+
+import argparse
+import json
+import os
+import re
+import sys
+
+sys.path.insert(
+    0,
+    os.path.join(
+        os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "mojom"))
+
+from mojom.generate.generator import WriteFile
+
+def ReadTypemap(path):
+  with open(path) as f:
+    return json.load(f)['c++']
+
+
+def LoadCppTypemapConfig(path):
+  configs = {}
+  with open(path) as f:
+    for config in json.load(f):
+      for entry in config['types']:
+        configs[entry['mojom']] = {
+            'typename': entry['cpp'],
+            'forward_declaration': entry.get('forward_declaration', None),
+            'public_headers': config.get('traits_headers', []),
+            'traits_headers': config.get('traits_private_headers', []),
+            'copyable_pass_by_value': entry.get('copyable_pass_by_value',
+                                                False),
+            'default_constructible': entry.get('default_constructible', True),
+            'force_serialize': entry.get('force_serialize', False),
+            'hashable': entry.get('hashable', False),
+            'move_only': entry.get('move_only', False),
+            'nullable_is_same_type': entry.get('nullable_is_same_type', False),
+            'non_copyable_non_movable': False,
+        }
+  return configs
+
+def main():
+  parser = argparse.ArgumentParser(
+      description=__doc__,
+      formatter_class=argparse.RawDescriptionHelpFormatter)
+  parser.add_argument(
+      '--dependency',
+      type=str,
+      action='append',
+      default=[],
+      help=('A path to another JSON typemap to merge into the output. '
+            'This may be repeated to merge multiple typemaps.'))
+  parser.add_argument(
+      '--cpp-typemap-config',
+      type=str,
+      action='store',
+      dest='cpp_config_path',
+      help=('A path to a single JSON-formatted typemap config as emitted by'
+            'GN when processing a mojom_cpp_typemap build rule.'))
+  parser.add_argument('--output',
+                      type=str,
+                      required=True,
+                      help='The path to which to write the generated JSON.')
+  params, _ = parser.parse_known_args()
+  typemaps = {}
+  if params.cpp_config_path:
+    typemaps = LoadCppTypemapConfig(params.cpp_config_path)
+  missing = [path for path in params.dependency if not os.path.exists(path)]
+  if missing:
+    raise IOError('Missing dependencies: %s' % ', '.join(missing))
+  for path in params.dependency:
+    typemaps.update(ReadTypemap(path))
+
+  WriteFile(json.dumps({'c++': typemaps}, indent=2), params.output)
+
+
+if __name__ == '__main__':
+  main()
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/minify_with_terser.py b/utils/codegen/ipc/mojo/public/tools/bindings/minify_with_terser.py
new file mode 100755
index 00000000..cefee7a4
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/minify_with_terser.py
@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+# Copyright 2023 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# This utility minifies JS files with terser.
+#
+# Instance of 'node' has no 'RunNode' member (no-member)
+# pylint: disable=no-member
+
+import argparse
+import os
+import sys
+
+_HERE_PATH = os.path.dirname(__file__)
+_SRC_PATH = os.path.normpath(os.path.join(_HERE_PATH, '..', '..', '..', '..'))
+_CWD = os.getcwd()
+sys.path.append(os.path.join(_SRC_PATH, 'third_party', 'node'))
+import node
+import node_modules
+
+
+def MinifyFile(input_file, output_file):
+  node.RunNode([
+      node_modules.PathToTerser(), input_file, '--mangle', '--compress',
+      '--comments', 'false', '--output', output_file
+  ])
+
+
+def main(argv):
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--input', required=True)
+  parser.add_argument('--output', required=True)
+  args = parser.parse_args(argv)
+
+  # Delete the output file if it already exists. It may be a sym link to the
+  # input, because in non-optimized/pre-Terser builds the input file is copied
+  # to the output location with gn copy().
+  out_path = os.path.join(_CWD, args.output)
+  if (os.path.exists(out_path)):
+    os.remove(out_path)
+
+  MinifyFile(os.path.join(_CWD, args.input), out_path)
+
+
+if __name__ == '__main__':
+  main(sys.argv[1:])
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/mojom.gni b/utils/codegen/ipc/mojo/public/tools/bindings/mojom.gni
new file mode 100644
index 00000000..3f6e54e0
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/mojom.gni
@@ -0,0 +1,2118 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//third_party/closure_compiler/closure_args.gni")
+import("//third_party/closure_compiler/compile_js.gni")
+import("//third_party/protobuf/proto_library.gni")
+import("//ui/webui/resources/tools/generate_grd.gni")
+import("//ui/webui/webui_features.gni")
+
+import("//build/config/cast.gni")
+
+# TODO(rockot): Maybe we can factor these dependencies out of //mojo. They're
+# used to conditionally enable message ID scrambling in a way which is
+# consistent across toolchains and which is affected by branded vs non-branded
+# Chrome builds. Ideally we could create some generic knobs here that could be
+# flipped elsewhere though.
+import("//build/config/chrome_build.gni")
+import("//build/config/chromeos/ui_mode.gni")
+import("//build/config/features.gni")
+import("//build/config/nacl/config.gni")
+import("//build/toolchain/kythe.gni")
+import("//components/nacl/features.gni")
+import("//third_party/jinja2/jinja2.gni")
+import("//third_party/ply/ply.gni")
+import("//tools/ipc_fuzzer/ipc_fuzzer.gni")
+declare_args() {
+  # Indicates whether typemapping should be supported in this build
+  # configuration. This may be disabled when building external projects which
+  # depend on //mojo but which do not need/want all of the Chromium tree
+  # dependencies that come with typemapping.
+  #
+  # Note that (perhaps obviously) a huge amount of Chromium code will not build
+  # with typemapping disabled, so it is never valid to set this to |false| in
+  # any Chromium build configuration.
+  enable_mojom_typemapping = true
+
+  # Controls message ID scrambling behavior. If |true|, message IDs are
+  # scrambled (i.e. randomized based on the contents of //chrome/VERSION) on
+  # non-Chrome OS desktop platforms. Enabled on official builds by default.
+  # Set to |true| to enable message ID scrambling on a specific build.
+  # See also `enable_scrambled_message_ids` below for more details.
+  enable_mojom_message_id_scrambling = is_official_build
+
+  # Enables generating javascript fuzzing-related code and the bindings for the
+  # MojoLPM fuzzer targets. Off by default.
+  enable_mojom_fuzzer = false
+
+  # Enables Closure compilation of generated JS lite bindings. In environments
+  # where compilation is supported, any mojom target "foo" will also have a
+  # corresponding "foo_js_library_for_compile" target generated.
+  if (is_chromeos_ash) {
+    enable_mojom_closure_compile = enable_js_type_check && optimize_webui
+  }
+}
+
+# Closure libraries are needed for mojom_closure_compile, and when
+# js_type_check is enabled on Ash.
+if (is_chromeos_ash) {
+  generate_mojom_closure_libraries =
+      enable_mojom_closure_compile || enable_js_type_check
+} else {
+  generate_mojom_closure_libraries = false
+}
+
+# NOTE: We would like to avoid scrambling message IDs where it doesn't add
+# value, so we limit the behavior to desktop builds for now. There is some
+# redundancy in the conditions here, but it is tolerated for clarity:
+# We're explicit about Mac, Windows, and Linux desktop support, but it's
+# also necessary to ensure that bindings in alternate toolchains (e.g.
+# NaCl IRT) are always consistent with the default toolchain; for that
+# reason we always enable scrambling within NaCl toolchains when possible,
+# as well as within the default toolchain when NaCl is enabled.
+#
+# Finally, because we *cannot* enable scrambling on Chrome OS (it would break
+# ARC) we have to explicitly opt out there even when NaCl is enabled (and
+# consequently also when building for NaCl toolchains.) For this reason we
+# check |target_os| explicitly, as it's consistent across all toolchains.
+#
+# TODO(crbug.com/1052397): Remove !chromeos_is_browser_only once
+# lacros-chrome switches to target_os="chromeos"
+enable_scrambled_message_ids =
+    enable_mojom_message_id_scrambling &&
+    (is_mac || is_win || (is_linux && !is_castos) ||
+     ((enable_nacl || is_nacl) &&
+      (target_os != "chromeos" && !chromeos_is_browser_only)))
+
+_mojom_tools_root = "//mojo/public/tools"
+_mojom_library_root = "$_mojom_tools_root/mojom/mojom"
+mojom_parser_script = "$_mojom_tools_root/mojom/mojom_parser.py"
+mojom_parser_sources = [
+  "$_mojom_library_root/__init__.py",
+  "$_mojom_library_root/error.py",
+  "$_mojom_library_root/fileutil.py",
+  "$_mojom_library_root/generate/__init__.py",
+  "$_mojom_library_root/generate/check.py",
+  "$_mojom_library_root/generate/generator.py",
+  "$_mojom_library_root/generate/module.py",
+  "$_mojom_library_root/generate/pack.py",
+  "$_mojom_library_root/generate/template_expander.py",
+  "$_mojom_library_root/generate/translate.py",
+  "$_mojom_library_root/parse/__init__.py",
+  "$_mojom_library_root/parse/ast.py",
+  "$_mojom_library_root/parse/conditional_features.py",
+  "$_mojom_library_root/parse/lexer.py",
+  "$_mojom_library_root/parse/parser.py",
+  "//tools/diagnosis/crbug_1001171.py",
+]
+
+mojom_generator_root = "$_mojom_tools_root/bindings"
+mojom_generator_script = "$mojom_generator_root/mojom_bindings_generator.py"
+mojom_generator_sources =
+    mojom_parser_sources + [
+      "$mojom_generator_root/checks/__init__.py",
+      "$mojom_generator_root/checks/mojom_attributes_check.py",
+      "$mojom_generator_root/checks/mojom_definitions_check.py",
+      "$mojom_generator_root/checks/mojom_interface_feature_check.py",
+      "$mojom_generator_root/checks/mojom_restrictions_check.py",
+      "$mojom_generator_root/generators/__init__.py",
+      "$mojom_generator_root/generators/cpp_util.py",
+      "$mojom_generator_root/generators/mojom_cpp_generator.py",
+      "$mojom_generator_root/generators/mojom_java_generator.py",
+      "$mojom_generator_root/generators/mojom_js_generator.py",
+      "$mojom_generator_root/generators/mojom_mojolpm_generator.py",
+      "$mojom_generator_root/generators/mojom_ts_generator.py",
+      "$mojom_generator_script",
+      "//build/action_helpers.py",
+      "//build/gn_helpers.py",
+      "//build/zip_helpers.py",
+    ]
+
+if (enable_scrambled_message_ids) {
+  declare_args() {
+    # The path to a file whose contents can be used as the basis for a message
+    # ID scrambling salt.
+    mojom_message_id_salt_path = "//chrome/VERSION"
+  }
+
+  assert(mojom_message_id_salt_path != "")
+  message_scrambling_args = [
+    "--scrambled_message_id_salt_path",
+    rebase_path(mojom_message_id_salt_path, root_build_dir),
+  ]
+  message_scrambling_inputs = [ mojom_message_id_salt_path ]
+} else {
+  message_scrambling_args = []
+  message_scrambling_inputs = []
+}
+
+# Generates targets for building C++, JavaScript and Java bindings from mojom
+# files. The output files will go under the generated file directory tree with
+# the same path as each input file.
+#
+# Other targets should depend on one of these generated targets (where "foo"
+# is the target name):
+#
+#   foo
+#       C++ bindings.
+#
+#   foo_blink
+#       C++ bindings using Blink standard types.
+#
+#   foo_java
+#       Java bindings.
+#
+#   foo_js
+#       JavaScript bindings; used as compile-time dependency.
+#
+#   foo_js_data_deps
+#       JavaScript bindings; used as run-time dependency.
+#
+# Parameters:
+#
+#   sources (optional if one of the deps sets listed below is present)
+#       List of source .mojom files to compile.
+#
+#   deps (optional)
+#       Note: this can contain only other mojom targets.
+#
+#       DEPRECATED: This is synonymous with public_deps because all mojom
+#       dependencies must be public by design. Please use public_deps.
+#
+#   public_deps (optional)
+#       Note: this can contain only other mojom targets.
+#
+#   parser_deps (optional)
+#       List of non-mojom targets required for the mojom sources to be parsed.
+#
+#   import_dirs (optional)
+#       List of import directories that will get added when processing sources.
+#
+#   input_root_override (optional)
+#       Root path for the .mojom files used to generate the namespaces for
+#       interfaces. Useful with targets outside //, e.g. in parent directories
+#       above "//". The default input root is //
+#       Example: Vivaldi's source root is "//vivaldi/",
+#       and "//vivaldi/chromium/" is "//"
+#       In such cases, not using this argument lead to the output files being
+#       located in different directories than expected.
+#
+#   testonly (optional)
+#
+#   visibility (optional)
+#
+#   visibility_blink (optional)
+#       The value to use for visibility for the blink variant. If unset,
+#       |visibility| is used.
+#
+#   cpp_only (optional)
+#       If set to true, only the C++ bindings targets will be generated.
+#
+#       NOTE: If the global |enable_mojom_fuzzer| build arg is true, JS bindings
+#       will still be generated even when |cpp_only| is set to |true|, unless
+#       you also set |enable_fuzzing| to |false| in your mojom target.
+#
+#   cpp_typemaps (optional)
+#       A list of typemaps to be applied to the generated C++ bindings for this
+#       mojom target. Note that this only applies to the non-Blink variant of
+#       generated C++ bindings.
+#
+#       Every typemap is a GN scope describing how one or more mojom types maps
+#       to a non-mojom C++ type, including necessary deps and headers required
+#       for the mapping to work. See the Typemaps section below.
+#
+#   blink_cpp_typemaps (optional)
+#       Same as above, but for the Blink variant of generated C++ bindings.
+#
+#   cpp_proxy_target (optional)
+#       The name of a target which all C++ dependencies will link against
+#       instead of linking directly against this mojom target's generated C++
+#       sources. Normally when declaring invoking the mojom("foo") target, GN
+#       emits a source_set or component target named "foo" which encompasses the
+#       default variant of generated C++ bindings. This changes that to instead
+#       emit a group("foo") which merely forwards public_deps to the named
+#       `cpp_proxy_target`. That target must in turn depend on
+#       "foo_cpp_sources".
+#
+#       This is useful primarily in conjunction with export_define et al to
+#       embed generated C++ bindings within an existing component target.
+#
+#   blink_cpp_proxy_target (optional)
+#       Same concept as `cpp_proxy_target` above, but affects the generated
+#       "foo_blink" Blink-variant C++ bindings.
+#
+#   cpp_configs (optional)
+#       A list of extra configs to apply to the default variant of generated C++
+#       bindings.
+#
+#   blink_cpp_configs (optional)
+#       A list of extra configs to apply to the Blink variant of generated C++
+#       bindings.
+#
+#   mojom_source_deps (optional)
+#       A list of mojoms this target depends upon. This is equivalent to
+#       public_deps except that the C++ bindings depend on each of the named
+#       "foo" targets' "foo_cpp_sources" rather than on foo's
+#       `cpp_proxy_target`. It only makes sense to use this for dependencies
+#       that set `cpp_proxy_target`, and only when the dependent mojom() would
+#       otherwise have circular dependencies with that proxy target.
+#
+#   mojom_blink_source_deps (optional)
+#       Same as above but depends on "foo_blink_cpp_sources" and is used for
+#       dependencies that specify a `blink_cpp_proxy_target`.
+#
+#   generate_java (optional)
+#       If set to true, Java bindings are generated for Android builds. If
+#       |cpp_only| is set to true, it overrides this to prevent generation of
+#       Java bindings.
+#
+#   enable_js_fuzzing (optional)
+#       Enables generation of javascript fuzzing sources for the target if the
+#       global build arg |enable_mojom_fuzzer| is also set to |true|.
+#       Defaults to |true|. If JS fuzzing generation is enabled for a target,
+#       the target will always generate JS bindings even if |cpp_only| is set to
+#       |true|. See note above.
+#
+#   enable_mojolpm_fuzzing (optional)
+#       Enables generation of fuzzing sources for the target if the global build
+#       arg |enable_mojom_fuzzer| is also set to |true|. Defaults to |true|.
+#
+#   support_lazy_serialization (optional)
+#       If set to |true|, generated C++ bindings will effectively prefer to
+#       transmit messages in an unserialized form when going between endpoints
+#       in the same process. This avoids the runtime cost of serialization,
+#       deserialization, and validation logic at the expensive of increased
+#       code size. Defaults to |false|.
+#
+#   disable_variants (optional)
+#       If |true|, no variant sources will be generated for the target. Defaults
+#       to |false|.
+#
+#   disallow_native_types (optional)
+#       If set to |true|, mojoms in this target may not apply the [Native]
+#       attribute to struct or enum declarations. This avoids emitting code
+#       which depends on legacy IPC serialization. Default is |false|, meaning
+#       [Native] types are allowed.
+#
+#   disallow_interfaces (optional)
+#       If set to |true|, mojoms in this target may not define interfaces.
+#       Generates bindings with a smaller set of dependencies. Defaults to
+#       |false|.
+#
+#   scramble_message_ids (optional)
+#       If set to |true| (the default), generated mojom interfaces will use
+#       scrambled ordinal identifiers in encoded messages.
+#
+#   component_output_prefix (optional)
+#       The prefix to use for the output_name of any component library emitted
+#       for generated C++ bindings. If this is omitted, C++ bindings targets are
+#       emitted as source_sets instead. Because this controls the name of the
+#       output shared library binary in the root output directory, it must be
+#       unique across the entire build configuration.
+#
+#       This is required if |component_macro_prefix| is specified.
+#
+#   component_macro_prefix (optional)
+#       This specifies a macro prefix to use for component export macros and
+#       should therefore be globally unique in the project. For example if this
+#       is "FOO_BAR", then the generated C++ sources will be built with
+#       IS_FOO_BAR_{suffix}_IMPL defined, and the generated public headers will
+#       annotate public symbol definitions with
+#       COMPONENT_EXPORT(FOO_BAR_{suffix}). "suffix" in this case depends on
+#       which internal subtarget is generating the code (e.g. "SHARED", or a
+#       variant name like "BLINK").
+#
+#   enabled_features (optional)
+#       Definitions in a mojom file can be guarded by an EnableIf attribute. If
+#       the value specified by the attribute does not match any items in the
+#       list of enabled_features, the definition will be disabled, with no code
+#       emitted for it.
+#
+#   generate_closure_exports (optional)
+#       Generates JS lite bindings will use goog.provide and goog.require
+#       annotations to export its symbols and import core Mojo bindings support
+#       and other mojom dependency modules. Use this if you plan to compile your
+#       bindings into a larger JS binary. Defaults to |false|, instead
+#       generating JS lite bindings which assume they will be manually loaded in
+#       correct dependency order. Note that this only has an effect if
+#       the |enable_mojom_closure_compile| global arg is set to |true| as well.
+#
+#   generate_webui_js_bindings (optional)
+#       Generate WebUI bindings in JavaScript rather than TypeScript. Defaults
+#       to false. ChromeOS only parameter.
+#
+#   generate_legacy_js_bindings (optional)
+#       Generate js_data_deps target containing legacy JavaScript bindings files
+#       for Blink tests and other non-WebUI users when generating TypeScript
+#       bindings for WebUI. Ignored if generate_webui_js_bindings is set to
+#       true.
+#
+#   js_generate_struct_deserializers (optional)
+#       Generates JS deerialize methods for structs.
+#
+#   extra_cpp_template_paths (optional)
+#       List of extra C++ templates that are used to generate additional source
+#       and/or header files. The templates should end with extension ".tmpl".
+#
+#   webui_module_path (optional)
+#       The path or URL at which modules generated by this target will be
+#       accessible to WebUI pages. This may either be an absolute path or
+#       a full URL path starting with "chrome://resources/mojo". If this path
+#       is not specified, WebUI bindings will not be generated.
+#
+#       If an absolute path, a WebUI page may only import these modules if
+#       they are added to that page's data source (usually by adding the
+#       modules to the mojo_files list for build_webui(), or by listing the
+#       files as inputs to the page's ts_library() and/or generate_grd() build
+#       steps.
+#
+#       If this is is instead a URL string starting with
+#       "chrome://resources/mojo", the resulting bindings files should
+#       be added to one of the lists in ui/webui/resources/mojo/BUILD.gn,
+#       at which point they will be made available to all WebUI pages at the
+#       given URL.
+#
+#       Note: WebUI module bindings are generated in TypeScript by default,
+#       unless |generate_webui_js_bindings| is specified as true.
+#
+# The following parameters are used to support the component build. They are
+# needed so that bindings which are linked with a component can use the same
+# export settings for classes. The first three are for the chromium variant, and
+# the last three are for the blink variant. These parameters can also override
+# |component_macro_prefix| for a specific variant, allowing e.g. one variant
+# to be linked into a larger non-mojom component target, while all other
+# variants get their own unique component target.
+#   export_class_attribute (optional)
+#       The attribute to add to the class declaration. e.g. "CONTENT_EXPORT"
+#   export_define (optional)
+#       A define to be added to the source_set which is needed by the export
+#       header. e.g. "CONTENT_IMPLEMENTATION=1"
+#   export_header (optional)
+#       A header to be added to the generated bindings to support the component
+#       build. e.g. "content/common/content_export.h"
+#   export_class_attribute_blink (optional)
+#   export_define_blink (optional)
+#   export_header_blink (optional)
+#       These three parameters are the blink variants of the previous 3.
+#
+# The following parameters are used to correct component build dependencies.
+# They are needed so mojom-mojom dependencies follow the rule that dependencies
+# on a source set in another component are replaced by a dependency on the
+# containing component. The first two are for the chromium variant; the other
+# two are for the blink variant.
+#   overridden_deps (optional)
+#       The list of mojom deps to be overridden.
+#   component_deps (optional)
+#       The list of component deps to add to replace overridden_deps.
+#   overridden_deps_blink (optional)
+#   component_deps_blink (optional)
+#       These two parameters are the blink variants of the previous two.
+#
+#   check_includes_blink (optional)
+#       Overrides the check_includes variable for the blink variant.
+#       If check_includes_blink is not defined, the check_includes variable
+#       retains its original value.
+#
+# Typemaps
+# ========
+# The cpp_typemaps and blink_cpp_typemaps each specify an optional list of
+# typemapping configurations. Each configuration is a GN scope with metadata
+# describing what and how to map.
+#
+# Typemap scope parameters:
+#   types
+#       A list of type specifications for this typemap. Each type specification
+#       is a nested GN scope which can be expressed with the following syntax:
+#
+#           {
+#             mojom = "foo.mojom.Bar"
+#             cpp = "::foo::LegitBar"
+#             move_only = true
+#             # etc...
+#           }
+#
+#       Each type specification supports the following values:
+#
+#         mojom (required)
+#             The fully qualified name of a mojom type to be mapped. This is a
+#             string like "foo.mojom.Bar".
+#
+#         cpp (required)
+#             The fully qualified name of the C++ type to which the mojom type
+#             should be mapped in generated bindings. This is a string like
+#             "::base::Value" or "std::vector<::base::Value>".
+#
+#         copyable_pass_by_value (optional)
+#             A boolean value (default false) which effectively indicates
+#             whether the C++ type is very cheap to copy. If so, generated
+#             bindings will pass by value but not use std::move() at call sites.
+#
+#         default_constructible (optional)
+#             A boolean value (default true) which indicates whether the C++
+#             type is default constructible. If a C++ type is not default
+#             constructible (e.g. the implementor of the type prefers not to
+#             publicly expose a default constructor that creates an object in an
+#             invalid state), Mojo will instead construct C++ type with an
+#             argument of the type `mojo::DefaultConstruct::Tag` (essentially a
+#             passkey-like type specifically for this use case).
+#
+#         force_serialize (optional)
+#             A boolean value (default false) which disables lazy serialization
+#             of the typemapped type if lazy serialization is enabled for the
+#             mojom target applying this typemap.
+#
+#         forward_declaration (optional)
+#             A forward declaration of the C++ type, which bindings that don't
+#             need the full type definition can use to reduce the size of
+#             the generated code. This is a string like
+#             "namespace base { class Value; }".
+#
+#         hashable (optional)
+#             A boolean value (default false) indicating whether the C++ type is
+#             hashable. Set to true if true AND needed (i.e. you need to use the
+#             type as the key of a mojom map).
+#
+#         move_only (optional)
+#             A boolean value (default false) which indicates whether the C++
+#             type is move-only. If true, generated bindings will pass the type
+#             by value and use std::move() at call sites.
+#
+#         nullable_is_same_type (optional)
+#             A boolean value (default false) which indicates that the C++ type
+#             has some baked-in semantic notion of a "null" state. If true, the
+#             traits for the type must define IsNull and SetToNull methods.
+#
+#             When false, nullable fields are represented by wrapping the C++
+#             type with absl::optional, and null values are simply
+#             absl::nullopt.
+#
+# Additional typemap scope parameters:
+#
+#   traits_headers (optional)
+#       Headers which must be included in the generated mojom in order for
+#       serialization to be possible. This generally means including at least
+#       the header for the corresponding mojom traits definitions.
+#
+#   traits_private_headers (optional)
+#       Headers which must be included in generated C++ serialization code for
+#       a mojom using the typemap. This should be used only when including a
+#       header in |traits_headers| is problematic for compilation, as is
+#       sometimes the case with legacy IPC message headers.
+#
+#   traits_sources (optional)
+#       The references to the source files (typically a single .cc and .h file)
+#       defining an appropriate set of EnumTraits or StructTraits, etc for the
+#       the type-mapping. Using this will cause the listed sources to be
+#       integrated directly into the dependent mojom's generated type-mapping
+#       targets.
+#
+#       Prefer using |traits_public_deps| over inlined |traits_sources|, as this
+#       will generally lead to easier build maintenance over time.
+#
+#       NOTE: If a typemap is shared by Blink and non-Blink bindings, you cannot
+#       use this and MUST use |traits_public_deps| to reference traits built
+#       within a separate target.
+#
+#   traits_deps / traits_public_deps (optional)
+#       Any dependencies of sources in |traits_headers| or |traits_sources| must
+#       be listed here.
+#
+template("mojom") {
+  assert(
+      defined(invoker.sources) || defined(invoker.deps) ||
+          defined(invoker.public_deps),
+      "\"sources\" or \"deps\" must be defined for the $target_name template.")
+
+  if (defined(invoker.export_class_attribute) ||
+      defined(invoker.export_define) || defined(invoker.export_header)) {
+    assert(defined(invoker.export_class_attribute))
+    assert(defined(invoker.export_define) || defined(invoker.cpp_configs))
+    assert(defined(invoker.export_header))
+  }
+  if (defined(invoker.export_class_attribute_blink) ||
+      defined(invoker.export_define_blink) ||
+      defined(invoker.export_header_blink)) {
+    assert(defined(invoker.export_class_attribute_blink))
+    assert(defined(invoker.export_define_blink) ||
+           defined(invoker.blink_cpp_configs))
+    assert(defined(invoker.export_header_blink))
+
+    # Not all platforms use the Blink variant, so make sure GN doesn't complain
+    # about these values being inconsequential.
+    not_needed(invoker,
+               [
+                 "export_class_attribute_blink",
+                 "export_define_blink",
+                 "export_header_blink",
+               ])
+  }
+  if (defined(invoker.overridden_deps) || defined(invoker.component_deps)) {
+    assert(defined(invoker.overridden_deps))
+    assert(defined(invoker.component_deps))
+  }
+
+  if (defined(invoker.overridden_deps_blink) ||
+      defined(invoker.component_deps_blink)) {
+    assert(defined(invoker.overridden_deps_blink))
+    assert(defined(invoker.component_deps_blink))
+  }
+
+  # Type-mapping may be disabled or we may not generate C++ bindings.
+  not_needed(invoker,
+             [
+               "cpp_typemaps",
+               "blink_cpp_typemaps",
+             ])
+
+  require_full_cpp_deps =
+      !defined(invoker.disallow_native_types) ||
+      !invoker.disallow_native_types || !defined(invoker.disallow_interfaces) ||
+      !invoker.disallow_interfaces
+
+  all_deps = []
+  mojom_cpp_deps = []
+  if (defined(invoker.deps)) {
+    all_deps += invoker.deps
+    mojom_cpp_deps += invoker.deps
+  }
+  if (defined(invoker.public_deps)) {
+    all_deps += invoker.public_deps
+    mojom_cpp_deps += invoker.public_deps
+  }
+  if (defined(invoker.mojom_source_deps)) {
+    all_deps += invoker.mojom_source_deps
+  }
+  if (defined(invoker.mojom_blink_source_deps)) {
+    all_deps += invoker.mojom_blink_source_deps
+  }
+  not_needed([ "mojom_deps" ])
+
+  if (defined(invoker.component_macro_prefix)) {
+    assert(defined(invoker.component_output_prefix))
+  }
+
+  group("${target_name}__is_mojom") {
+  }
+
+  # Explicitly ensure that all dependencies (invoker.deps and
+  # invoker.public_deps) are mojom targets.
+  group("${target_name}__check_deps_are_all_mojom") {
+    deps = []
+    foreach(d, all_deps) {
+      name = get_label_info(d, "label_no_toolchain")
+      toolchain = get_label_info(d, "toolchain")
+      deps += [ "${name}__is_mojom(${toolchain})" ]
+    }
+  }
+
+  sources_list = []
+  if (defined(invoker.sources)) {
+    sources_list = invoker.sources
+  }
+
+  # Listed sources may be relative to the current target dir, or they may be
+  # absolute paths, including paths to generated mojom files. While those are
+  # fine as-is for input references, deriving output paths can be more subtle.
+  #
+  # Here we rewrite all source paths to be relative to the root build dir and
+  # strip any root_gen_dir prefixes.
+  #
+  # So for a target in //foo/bar with:
+  #
+  #     sources = [
+  #       "a.mojom",
+  #       "b/c.mojom",
+  #       "//baz/d.mojom",
+  #       "$target_gen_dir/e.mojom",
+  #     ]
+  #
+  # output_file_base_paths will be:
+  #
+  #     [
+  #       "foo/bar/a.mojom",
+  #       "foo/bar/b/c.mojom",
+  #       "baz/d.mojom",
+  #       "foo/bar/e.mojom",
+  #     ]
+  #
+  # This result is essentially a list of base filename paths which are suitable
+  # for the naming of any generated output files derived from their
+  # corresponding input mojoms. These paths are always considered to be relative
+  # to root_gen_dir.
+  if (defined(invoker.input_root_override)) {
+    source_abspaths = rebase_path(sources_list, invoker.input_root_override)
+  } else {
+    source_abspaths = rebase_path(sources_list, "//")
+  }
+  output_file_base_paths = []
+  foreach(path, source_abspaths) {
+    output_file_base_paths +=
+        [ string_replace(path, rebase_path(root_gen_dir, "//") + "/", "") ]
+  }
+
+  # Sanity check that either all input files have a .mojom extension, or
+  # all input files have a .test-mojom extension AND |testonly| is |true|.
+  sources_list_filenames =
+      process_file_template(sources_list, "{{source_file_part}}")
+  sources_list_filenames_with_mojom_extension =
+      process_file_template(sources_list, "{{source_name_part}}.mojom")
+  if (sources_list_filenames != sources_list_filenames_with_mojom_extension) {
+    sources_list_filenames_with_test_mojom_extension =
+        process_file_template(sources_list, "{{source_name_part}}.test-mojom")
+    if (sources_list_filenames ==
+        sources_list_filenames_with_test_mojom_extension) {
+      assert(
+          defined(invoker.testonly) && invoker.testonly,
+          "mojom targets for .test-mojom files must set |testonly| to |true|")
+    } else {
+      assert(
+          false,
+          "One or more mojom files has an invalid extension. The only " +
+              "allowed extensions are .mojom and .test-mojom, and any given " +
+              "mojom target must use one or the other exclusively.")
+    }
+  }
+
+  build_metadata_filename = "$target_gen_dir/$target_name.build_metadata"
+  build_metadata = {
+  }
+  build_metadata.sources = rebase_path(sources_list, target_gen_dir)
+  build_metadata.deps = []
+  foreach(dep, all_deps) {
+    dep_target_gen_dir = get_label_info(dep, "target_gen_dir")
+    dep_name = get_label_info(dep, "name")
+    build_metadata.deps +=
+        [ rebase_path("$dep_target_gen_dir/$dep_name.build_metadata",
+                      target_gen_dir) ]
+  }
+  write_file(build_metadata_filename, build_metadata, "json")
+
+  generate_js_fuzzing =
+      (!defined(invoker.enable_js_fuzzing) || invoker.enable_js_fuzzing) &&
+      enable_mojom_fuzzer && (!defined(invoker.testonly) || !invoker.testonly)
+
+  generate_mojolpm_fuzzing =
+      (!defined(invoker.enable_mojolpm_fuzzing) ||
+       invoker.enable_mojolpm_fuzzing) && enable_mojom_fuzzer &&
+      (!defined(invoker.testonly) || !invoker.testonly)
+
+  parser_target_name = "${target_name}__parser"
+  parser_deps = []
+  foreach(dep, all_deps) {
+    _label = get_label_info(dep, "label_no_toolchain")
+    parser_deps += [ "${_label}__parser" ]
+  }
+  if (defined(invoker.parser_deps)) {
+    parser_deps += invoker.parser_deps
+  }
+  if (sources_list == []) {
+    # Even without sources we generate a parser target to at least forward
+    # other parser dependencies.
+    group(parser_target_name) {
+      public_deps = parser_deps
+    }
+  } else {
+    enabled_features = []
+    if (defined(invoker.enabled_features)) {
+      enabled_features += invoker.enabled_features
+    }
+    if (is_posix) {
+      enabled_features += [ "is_posix" ]
+    }
+    if (is_android) {
+      enabled_features += [ "is_android" ]
+    } else if (is_chromeos_ash) {
+      enabled_features += [
+        "is_chromeos",
+        "is_chromeos_ash",
+      ]
+    } else if (is_chromeos_lacros) {
+      enabled_features += [
+        "is_chromeos",
+        "is_chromeos_lacros",
+      ]
+    } else if (is_fuchsia) {
+      enabled_features += [ "is_fuchsia" ]
+    } else if (is_ios) {
+      enabled_features += [ "is_ios" ]
+    } else if (is_linux) {
+      enabled_features += [ "is_linux" ]
+    } else if (is_mac) {
+      enabled_features += [ "is_mac" ]
+    } else if (is_win) {
+      enabled_features += [ "is_win" ]
+    }
+
+    if (is_apple) {
+      enabled_features += [ "is_apple" ]
+    }
+
+    action(parser_target_name) {
+      allow_remote = true
+      custom_processor = "mojom_parser"
+      script = mojom_parser_script
+      inputs = mojom_parser_sources + ply_sources + [ build_metadata_filename ]
+      sources = sources_list
+      public_deps = parser_deps
+      outputs = []
+      foreach(base_path, output_file_base_paths) {
+        filename = get_path_info(base_path, "file")
+        dirname = get_path_info(base_path, "dir")
+        outputs += [ "$root_gen_dir/$dirname/${filename}-module" ]
+      }
+
+      filelist = []
+      foreach(source, sources_list) {
+        filelist += [ rebase_path(source, root_build_dir) ]
+      }
+
+      # Workaround for https://github.com/ninja-build/ninja/issues/1966.
+      rsp_file = "$target_gen_dir/${target_name}.rsp"
+      write_file(rsp_file, filelist)
+      inputs += [ rsp_file ]
+
+      args = [
+        # Resolve relative input mojom paths against both the root src dir and
+        # the root gen dir.
+        "--input-root",
+        rebase_path("//.", root_build_dir),
+        "--input-root",
+        rebase_path(root_gen_dir, root_build_dir),
+
+        "--output-root",
+        rebase_path(root_gen_dir, root_build_dir),
+
+        "--mojom-file-list=" + rebase_path(rsp_file, root_build_dir),
+
+        "--check-imports",
+        rebase_path(build_metadata_filename, root_build_dir),
+      ]
+
+      if (defined(invoker.input_root_override)) {
+        args += [
+          "--input-root",
+          rebase_path(invoker.input_root_override, root_build_dir),
+        ]
+      }
+
+      foreach(enabled_feature, enabled_features) {
+        args += [
+          "--enable-feature",
+          enabled_feature,
+        ]
+      }
+
+      if (defined(invoker.webui_module_path)) {
+        args += [
+          "--add-module-metadata",
+          "webui_module_path=${invoker.webui_module_path}",
+        ]
+        if (defined(invoker.generate_webui_js_bindings) &&
+            invoker.generate_webui_js_bindings) {
+          args += [
+            "--add-module-metadata",
+            "generate_webui_js=True",
+          ]
+        }
+      }
+    }
+  }
+
+  generator_cpp_message_ids_target_name = "${target_name}__generate_message_ids"
+
+  # Generate code that is shared by different variants.
+  if (sources_list != []) {
+    base_dir = "//"
+    if (defined(invoker.input_root_override)) {
+      base_dir = invoker.input_root_override
+    }
+
+    common_generator_args = [
+      "--use_bundled_pylibs",
+      "-o",
+      rebase_path(root_gen_dir, root_build_dir),
+      "generate",
+      "-d",
+      rebase_path(base_dir, root_build_dir),
+      "-I",
+      rebase_path("//", root_build_dir),
+      "--bytecode_path",
+      rebase_path("$root_gen_dir/mojo/public/tools/bindings", root_build_dir),
+    ]
+    if (defined(invoker.input_root_override)) {
+      common_generator_args += [
+        "-I",
+        rebase_path(invoker.input_root_override, root_build_dir),
+      ]
+    }
+
+    if (defined(invoker.disallow_native_types) &&
+        invoker.disallow_native_types) {
+      common_generator_args += [ "--disallow_native_types" ]
+    }
+
+    if (defined(invoker.disallow_interfaces) && invoker.disallow_interfaces) {
+      common_generator_args += [ "--disallow_interfaces" ]
+    }
+
+    if (defined(invoker.import_dirs)) {
+      foreach(import_dir, invoker.import_dirs) {
+        common_generator_args += [
+          "-I",
+          rebase_path(import_dir, root_build_dir),
+        ]
+      }
+    }
+
+    if (defined(invoker.component_macro_prefix)) {
+      shared_component_export_macro =
+          "COMPONENT_EXPORT(${invoker.component_macro_prefix}_SHARED)"
+      shared_component_impl_macro =
+          "IS_${invoker.component_macro_prefix}_SHARED_IMPL"
+      shared_component_output_name = "${invoker.component_output_prefix}_shared"
+    } else if (defined(invoker.export_class_attribute_shared) ||
+               defined(invoker.export_class_attribute)) {
+      if (defined(invoker.export_class_attribute_shared)) {
+        assert(defined(invoker.export_header_shared))
+        shared_component_export_macro = invoker.export_class_attribute_shared
+        shared_component_impl_macro = invoker.export_define_shared
+      } else {
+        assert(!defined(invoker.export_header_shared))
+
+        # If no explicit shared attribute/define was provided by the invoker,
+        # we derive some reasonable settings frorm the default variant.
+        shared_component_export_macro = "COMPONENT_EXPORT(MOJOM_SHARED_" +
+                                        invoker.export_class_attribute + ")"
+        shared_component_impl_macro =
+            "IS_MOJOM_SHARED_" + invoker.export_class_attribute + "_IMPL"
+      }
+
+      if (defined(invoker.component_output_prefix)) {
+        shared_component_output_name =
+            "${invoker.component_output_prefix}_shared"
+      } else {
+        shared_component_output_name = "${target_name}_shared"
+      }
+    }
+
+    action(generator_cpp_message_ids_target_name) {
+      allow_remote = true
+      script = mojom_generator_script
+      inputs = mojom_generator_sources + jinja2_sources
+      sources = sources_list +
+                [ "$root_gen_dir/mojo/public/tools/bindings/cpp_templates.zip" ]
+      deps = [
+        ":$parser_target_name",
+        "//mojo/public/tools/bindings:precompile_templates",
+      ]
+      if (defined(invoker.parser_deps)) {
+        deps += invoker.parser_deps
+      }
+      outputs = []
+      args = common_generator_args
+      filelist = []
+      foreach(source, sources_list) {
+        filelist += [ rebase_path(source, root_build_dir) ]
+      }
+      foreach(base_path, output_file_base_paths) {
+        filename = get_path_info(base_path, "file")
+        dirname = get_path_info(base_path, "dir")
+        inputs += [ "$root_gen_dir/$dirname/${filename}-module" ]
+        outputs += [ "$root_gen_dir/$base_path-shared-message-ids.h" ]
+      }
+
+      # Workaround for https://github.com/ninja-build/ninja/issues/1966.
+      rsp_file = "$target_gen_dir/${target_name}.rsp"
+      write_file(rsp_file, filelist)
+      inputs += [ rsp_file ]
+
+      args += [
+        "--filelist=" + rebase_path(rsp_file, root_build_dir),
+        "--generate_non_variant_code",
+        "--generate_message_ids",
+        "-g",
+        "c++",
+      ]
+
+      if (!defined(invoker.scramble_message_ids) ||
+          invoker.scramble_message_ids) {
+        inputs += message_scrambling_inputs
+        args += message_scrambling_args
+      }
+    }
+
+    generator_shared_target_name = "${target_name}_shared__generator"
+
+    action(generator_shared_target_name) {
+      allow_remote = true
+      visibility = [ ":*" ]
+      script = mojom_generator_script
+      inputs = mojom_generator_sources + jinja2_sources
+      sources = sources_list +
+                [ "$root_gen_dir/mojo/public/tools/bindings/cpp_templates.zip" ]
+      deps = [
+        ":$parser_target_name",
+        "//mojo/public/tools/bindings:precompile_templates",
+      ]
+      if (defined(invoker.parser_deps)) {
+        deps += invoker.parser_deps
+      }
+
+      outputs = []
+      args = common_generator_args
+      filelist = []
+      foreach(source, sources_list) {
+        filelist += [ rebase_path(source, root_build_dir) ]
+      }
+      foreach(base_path, output_file_base_paths) {
+        # Need the mojom-module as an input to this action.
+        filename = get_path_info(base_path, "file")
+        dirname = get_path_info(base_path, "dir")
+        inputs += [ "$root_gen_dir/$dirname/${filename}-module" ]
+
+        outputs += [
+          "$root_gen_dir/$base_path-features.h",
+          "$root_gen_dir/$base_path-params-data.h",
+          "$root_gen_dir/$base_path-shared-internal.h",
+          "$root_gen_dir/$base_path-shared.cc",
+          "$root_gen_dir/$base_path-shared.h",
+        ]
+      }
+
+      # Workaround for https://github.com/ninja-build/ninja/issues/1966.
+      rsp_file = "$target_gen_dir/${target_name}.rsp"
+      write_file(rsp_file, filelist)
+      inputs += [ rsp_file ]
+
+      args += [
+        "--filelist=" + rebase_path(rsp_file, root_build_dir),
+        "--generate_non_variant_code",
+        "-g",
+        "c++",
+      ]
+
+      if (defined(shared_component_export_macro)) {
+        args += [
+          "--export_attribute",
+          shared_component_export_macro,
+          "--export_header",
+          "base/component_export.h",
+        ]
+      }
+
+      # Enable adding annotations to generated C++ headers that are used for
+      # cross-references in CodeSearch.
+      if (enable_kythe_annotations) {
+        args += [ "--enable_kythe_annotations" ]
+      }
+    }
+  } else {
+    group(generator_cpp_message_ids_target_name) {
+    }
+  }
+
+  shared_cpp_sources_target_name = "${target_name}_shared_cpp_sources"
+  source_set(shared_cpp_sources_target_name) {
+    if (defined(invoker.testonly)) {
+      testonly = invoker.testonly
+    }
+    configs += [ "//build/config/compiler:wexit_time_destructors" ]
+    deps = []
+    public_deps = []
+    if (output_file_base_paths != []) {
+      sources = []
+      foreach(base_path, output_file_base_paths) {
+        sources += [
+          "$root_gen_dir/$base_path-features.h",
+          "$root_gen_dir/$base_path-params-data.h",
+          "$root_gen_dir/$base_path-shared-internal.h",
+          "$root_gen_dir/$base_path-shared.cc",
+          "$root_gen_dir/$base_path-shared.h",
+        ]
+      }
+      public_deps += [ ":$generator_shared_target_name" ]
+    }
+    if (require_full_cpp_deps) {
+      public_deps += [ "//mojo/public/cpp/bindings" ]
+    } else {
+      public_deps += [ "//mojo/public/cpp/bindings:bindings_base" ]
+    }
+    foreach(d, all_deps) {
+      # Resolve the name, so that a target //mojo/something becomes
+      # //mojo/something:something and we can append shared_cpp_sources_suffix
+      # to get the cpp dependency name.
+      full_name = get_label_info("$d", "label_no_toolchain")
+      public_deps += [ "${full_name}_shared" ]
+    }
+    if (defined(shared_component_impl_macro)) {
+      defines = [ shared_component_impl_macro ]
+    }
+  }
+
+  shared_cpp_library_target_name = "${target_name}_shared"
+  if (defined(shared_component_output_name)) {
+    component(shared_cpp_library_target_name) {
+      if (defined(invoker.testonly)) {
+        testonly = invoker.testonly
+      }
+      output_name = "$shared_component_output_name"
+      public_deps = [ ":$shared_cpp_sources_target_name" ]
+    }
+  } else {
+    group(shared_cpp_library_target_name) {
+      if (defined(invoker.testonly)) {
+        testonly = invoker.testonly
+      }
+      public_deps = [ ":$shared_cpp_sources_target_name" ]
+    }
+  }
+
+  if (generate_mojolpm_fuzzing) {
+    # This block generates the proto files used for the MojoLPM fuzzer,
+    # and the corresponding proto targets that will be linked in the fuzzer
+    # targets. These are independent of the typemappings, and can be done
+    # separately here.
+
+    generator_mojolpm_proto_target_name =
+        "${target_name}_mojolpm_proto_generator"
+
+    action(generator_mojolpm_proto_target_name) {
+      allow_remote = true
+      script = mojom_generator_script
+      inputs = mojom_generator_sources + jinja2_sources
+      sources =
+          invoker.sources + [
+            "$root_gen_dir/mojo/public/tools/bindings/cpp_templates.zip",
+            "$root_gen_dir/mojo/public/tools/bindings/mojolpm_templates.zip",
+          ]
+      deps = [
+        ":$parser_target_name",
+        "//mojo/public/tools/bindings:precompile_templates",
+      ]
+
+      outputs = []
+      args = common_generator_args
+      filelist = []
+
+      # Split the input into generated and non-generated source files. They
+      # need to be processed separately.
+      gen_dir_path_wildcard = get_path_info("//", "gen_dir") + "/*"
+      non_gen_sources =
+          filter_exclude(invoker.sources, [ gen_dir_path_wildcard ])
+      gen_sources = filter_include(invoker.sources, [ gen_dir_path_wildcard ])
+
+      foreach(source, non_gen_sources) {
+        filelist += [ rebase_path(source, root_build_dir) ]
+        inputs += [ "$target_gen_dir/$source-module" ]
+        outputs += [ "$target_gen_dir/$source.mojolpm.proto" ]
+      }
+
+      foreach(source, gen_sources) {
+        filelist += [ rebase_path(source, root_build_dir) ]
+
+        # For generated files, we assume they're in the target_gen_dir or a
+        # sub-folder of it. Rebase the path so we can get the relative location.
+        source_file = rebase_path(source, target_gen_dir)
+        inputs += [ "$target_gen_dir/$source_file-module" ]
+        outputs += [ "$target_gen_dir/$source_file.mojolpm.proto" ]
+      }
+
+      # Workaround for https://github.com/ninja-build/ninja/issues/1966.
+      rsp_file = "$target_gen_dir/${target_name}.rsp"
+      write_file(rsp_file, filelist)
+      inputs += [ rsp_file ]
+
+      args += [
+        "--filelist=" + rebase_path(rsp_file, root_build_dir),
+        "--generate_non_variant_code",
+        "-g",
+        "mojolpm",
+      ]
+    }
+
+    mojolpm_proto_target_name = "${target_name}_mojolpm_proto"
+    if (defined(invoker.sources)) {
+      proto_library(mojolpm_proto_target_name) {
+        testonly = true
+        generate_python = false
+
+        # Split the input into generated and non-generated source files. They
+        # need to be processed separately.
+        gen_dir_path_wildcard = get_path_info("//", "gen_dir") + "/*"
+        non_gen_sources =
+            filter_exclude(invoker.sources, [ gen_dir_path_wildcard ])
+        gen_sources = filter_include(invoker.sources, [ gen_dir_path_wildcard ])
+        sources = process_file_template(
+                non_gen_sources,
+                [ "{{source_gen_dir}}/{{source_file_part}}.mojolpm.proto" ])
+        sources += process_file_template(
+                gen_sources,
+                [ "{{source_dir}}/{{source_file_part}}.mojolpm.proto" ])
+
+        import_dirs = [ "//" ]
+        proto_in_dir = "${root_gen_dir}"
+        proto_out_dir = "."
+        proto_deps = [ ":$generator_mojolpm_proto_target_name" ]
+        link_deps = [ "//mojo/public/tools/fuzzers:mojolpm_proto" ]
+
+        foreach(d, all_deps) {
+          # Resolve the name, so that a target //mojo/something becomes
+          # //mojo/something:something and we can append mojolpm_proto_suffix
+          # to get the proto dependency name.
+          full_name = get_label_info("$d", "label_no_toolchain")
+          proto_deps += [ "${full_name}_mojolpm_proto" ]
+          link_deps += [ "${full_name}_mojolpm_proto" ]
+        }
+      }
+    } else {
+      group(mojolpm_proto_target_name) {
+        testonly = true
+        public_deps = [ "//mojo/public/tools/fuzzers:mojolpm_proto" ]
+        if (defined(generator_shared_target_name)) {
+          public_deps += [ ":$generator_shared_target_name" ]
+        }
+        foreach(d, all_deps) {
+          # Resolve the name, so that a target //mojo/something becomes
+          # //mojo/something:something and we can append #mojolpm_proto_suffix
+          # to get the proto dependency name.
+          full_name = get_label_info("$d", "label_no_toolchain")
+          public_deps += [ "${full_name}_mojolpm_proto" ]
+        }
+      }
+    }
+  }
+
+  # Generate code for variants.
+  default_variant = {
+    component_macro_suffix = ""
+  }
+  if ((!defined(invoker.disable_variants) || !invoker.disable_variants) &&
+      use_blink) {
+    blink_variant = {
+      variant = "blink"
+      component_macro_suffix = "_BLINK"
+      for_blink = true
+    }
+    enabled_configurations = [
+      default_variant,
+      blink_variant,
+    ]
+  } else {
+    enabled_configurations = [ default_variant ]
+  }
+  foreach(bindings_configuration, enabled_configurations) {
+    cpp_only = false
+    if (defined(invoker.cpp_only)) {
+      cpp_only = invoker.cpp_only
+    }
+    variant_suffix = ""
+    if (defined(bindings_configuration.variant)) {
+      variant = bindings_configuration.variant
+      variant_suffix = "_${variant}"
+      cpp_only = true
+    }
+
+    cpp_typemap_configs = []
+    export_defines = []
+    export_defines_overridden = false
+    force_source_set = false
+    proxy_target = ""
+    extra_configs = []
+    output_visibility = []
+    output_visibility = [ "*" ]
+    cpp_source_deps = []
+    if (defined(bindings_configuration.for_blink) &&
+        bindings_configuration.for_blink) {
+      if (defined(invoker.blink_cpp_typemaps)) {
+        cpp_typemap_configs = invoker.blink_cpp_typemaps
+      }
+      if (defined(invoker.export_define_blink)) {
+        export_defines_overridden = true
+        export_defines = [ invoker.export_define_blink ]
+        force_source_set = true
+      }
+      if (defined(invoker.blink_cpp_configs)) {
+        extra_configs += invoker.blink_cpp_configs
+      }
+      if (defined(invoker.blink_cpp_proxy_target)) {
+        proxy_target = invoker.blink_cpp_proxy_target
+      }
+      if (defined(invoker.visibility_blink)) {
+        output_visibility = []
+        output_visibility = invoker.visibility_blink
+      }
+      if (defined(invoker.mojom_blink_source_deps)) {
+        cpp_source_deps = invoker.mojom_blink_source_deps
+      }
+    } else {
+      if (defined(invoker.cpp_typemaps)) {
+        cpp_typemap_configs = invoker.cpp_typemaps
+      }
+      if (defined(invoker.export_define)) {
+        export_defines_overridden = true
+        export_defines = [ invoker.export_define ]
+        force_source_set = true
+      }
+      if (defined(invoker.cpp_configs)) {
+        extra_configs += invoker.cpp_configs
+      }
+      if (defined(invoker.cpp_proxy_target)) {
+        proxy_target = invoker.cpp_proxy_target
+      }
+      if (defined(invoker.visibility)) {
+        output_visibility = []
+        output_visibility = invoker.visibility
+      }
+      if (defined(invoker.mojom_source_deps)) {
+        cpp_source_deps = invoker.mojom_source_deps
+      }
+    }
+    not_needed([ "cpp_typemap_configs" ])
+    if (proxy_target != "") {
+      group("${target_name}${variant_suffix}__has_cpp_proxy") {
+      }
+    }
+
+    if (!export_defines_overridden && defined(invoker.component_macro_prefix)) {
+      output_name_override =
+          "${invoker.component_output_prefix}${variant_suffix}"
+      export_defines =
+          [ "IS_${invoker.component_macro_prefix}" +
+            "${bindings_configuration.component_macro_suffix}_IMPL" ]
+    }
+
+    generate_java = false
+    if (!cpp_only && defined(invoker.generate_java)) {
+      generate_java = invoker.generate_java
+    }
+    type_mappings_target_name = "${target_name}${variant_suffix}__type_mappings"
+    type_mappings_path =
+        "$target_gen_dir/${target_name}${variant_suffix}__type_mappings"
+    if (sources_list != []) {
+      export_args = []
+      export_args_overridden = false
+      if (defined(bindings_configuration.for_blink) &&
+          bindings_configuration.for_blink) {
+        if (defined(invoker.export_class_attribute_blink)) {
+          export_args_overridden = true
+          export_args += [
+            "--export_attribute",
+            invoker.export_class_attribute_blink,
+            "--export_header",
+            invoker.export_header_blink,
+          ]
+        }
+      } else if (defined(invoker.export_class_attribute)) {
+        export_args_overridden = true
+        export_args += [
+          "--export_attribute",
+          invoker.export_class_attribute,
+          "--export_header",
+          invoker.export_header,
+        ]
+      }
+      if (!export_args_overridden && defined(invoker.component_macro_prefix)) {
+        export_args += [
+          "--export_attribute",
+          "COMPONENT_EXPORT(${invoker.component_macro_prefix}" +
+              "${bindings_configuration.component_macro_suffix})",
+          "--export_header",
+          "base/component_export.h",
+        ]
+      }
+
+      generator_cpp_output_suffixes = []
+      variant_dash_suffix = ""
+      if (defined(variant)) {
+        variant_dash_suffix = "-${variant}"
+      }
+      generator_cpp_output_suffixes += [
+        "${variant_dash_suffix}-forward.h",
+        "${variant_dash_suffix}-import-headers.h",
+        "${variant_dash_suffix}-test-utils.h",
+        "${variant_dash_suffix}.cc",
+        "${variant_dash_suffix}.h",
+      ]
+
+      generator_target_name = "${target_name}${variant_suffix}__generator"
+
+      # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
+      action(generator_target_name) {
+        allow_remote = true
+        visibility = [ ":*" ]
+        script = mojom_generator_script
+        inputs = mojom_generator_sources + jinja2_sources
+        sources =
+            sources_list + [
+              "$root_gen_dir/mojo/public/tools/bindings/cpp_templates.zip",
+              type_mappings_path,
+            ]
+        if (generate_mojolpm_fuzzing &&
+            !defined(bindings_configuration.variant)) {
+          sources += [
+            "$root_gen_dir/mojo/public/tools/bindings/mojolpm_templates.zip",
+          ]
+        }
+        deps = [
+          ":$parser_target_name",
+          ":$type_mappings_target_name",
+          "//mojo/public/tools/bindings:precompile_templates",
+        ]
+
+        if (defined(invoker.parser_deps)) {
+          deps += invoker.parser_deps
+        }
+        outputs = []
+        args = common_generator_args + export_args
+        filelist = []
+        foreach(source, sources_list) {
+          filelist += [ rebase_path(source, root_build_dir) ]
+        }
+        foreach(base_path, output_file_base_paths) {
+          filename = get_path_info(base_path, "file")
+          dirname = get_path_info(base_path, "dir")
+          inputs += [ "$root_gen_dir/$dirname/${filename}-module" ]
+
+          outputs += [
+            "$root_gen_dir/${base_path}${variant_dash_suffix}-forward.h",
+            "$root_gen_dir/${base_path}${variant_dash_suffix}-import-headers.h",
+            "$root_gen_dir/${base_path}${variant_dash_suffix}-test-utils.h",
+            "$root_gen_dir/${base_path}${variant_dash_suffix}.cc",
+            "$root_gen_dir/${base_path}${variant_dash_suffix}.h",
+          ]
+          if (generate_mojolpm_fuzzing &&
+              !defined(bindings_configuration.variant)) {
+            outputs += [
+              "$root_gen_dir/${base_path}${variant_dash_suffix}-mojolpm.cc",
+              "$root_gen_dir/${base_path}${variant_dash_suffix}-mojolpm.h",
+            ]
+          }
+        }
+
+        # Workaround for https://github.com/ninja-build/ninja/issues/1966.
+        rsp_file = "$target_gen_dir/${target_name}.rsp"
+        write_file(rsp_file, filelist)
+        inputs += [ rsp_file ]
+        args += [
+          "--filelist=" + rebase_path("$rsp_file", root_build_dir),
+          "-g",
+        ]
+
+        if (generate_mojolpm_fuzzing &&
+            !defined(bindings_configuration.variant)) {
+          args += [ "c++,mojolpm" ]
+        } else {
+          args += [ "c++" ]
+        }
+
+        if (defined(bindings_configuration.variant)) {
+          args += [
+            "--variant",
+            bindings_configuration.variant,
+          ]
+        }
+
+        args += [
+          "--typemap",
+          rebase_path(type_mappings_path, root_build_dir),
+        ]
+
+        if (defined(bindings_configuration.for_blink) &&
+            bindings_configuration.for_blink) {
+          args += [ "--for_blink" ]
+        }
+
+        if (defined(invoker.support_lazy_serialization) &&
+            invoker.support_lazy_serialization) {
+          args += [ "--support_lazy_serialization" ]
+        }
+
+        if (enable_kythe_annotations) {
+          args += [ "--enable_kythe_annotations" ]
+        }
+
+        if (!defined(invoker.scramble_message_ids) ||
+            invoker.scramble_message_ids) {
+          inputs += message_scrambling_inputs
+          args += message_scrambling_args
+        }
+
+        if (defined(invoker.extra_cpp_template_paths)) {
+          foreach(extra_cpp_template, invoker.extra_cpp_template_paths) {
+            args += [
+              "--extra_cpp_template_paths",
+              rebase_path(extra_cpp_template, root_build_dir),
+            ]
+            inputs += [ extra_cpp_template ]
+
+            assert(
+                get_path_info(extra_cpp_template, "extension") == "tmpl",
+                "--extra_cpp_template_paths only accepts template files ending in extension .tmpl")
+            foreach(base_path, output_file_base_paths) {
+              template_file_name = get_path_info("$extra_cpp_template", "name")
+              outputs += [ "$root_gen_dir/${base_path}${variant_dash_suffix}-${template_file_name}" ]
+            }
+          }
+        }
+      }
+    }
+
+    # Write the typemapping configuration for this target out to a file to be
+    # validated by a Python script. This helps catch mistakes that can't
+    # be caught by logic in GN.
+    _typemap_config_filename =
+        "$target_gen_dir/${target_name}${variant_suffix}.typemap_config"
+    _typemap_stamp_filename = "${_typemap_config_filename}.validated"
+    _typemap_validator_target_name = "${type_mappings_target_name}__validator"
+    _rebased_typemap_configs = []
+    foreach(config, cpp_typemap_configs) {
+      _rebased_config = {
+      }
+      _rebased_config = config
+      if (defined(config.traits_headers)) {
+        _rebased_config.traits_headers = []
+        _rebased_config.traits_headers =
+            rebase_path(config.traits_headers, "//")
+      }
+      if (defined(config.traits_private_headers)) {
+        _rebased_config.traits_private_headers = []
+        _rebased_config.traits_private_headers =
+            rebase_path(config.traits_private_headers, "//")
+      }
+      _rebased_typemap_configs += [ _rebased_config ]
+    }
+    write_file(_typemap_config_filename, _rebased_typemap_configs, "json")
+    _mojom_target_name = target_name
+
+    action(_typemap_validator_target_name) {
+      allow_remote = true
+      script = "$mojom_generator_root/validate_typemap_config.py"
+      inputs = [ _typemap_config_filename ]
+      outputs = [ _typemap_stamp_filename ]
+      args = [
+        get_label_info(_mojom_target_name, "label_no_toolchain"),
+        rebase_path(_typemap_config_filename, root_build_dir),
+        rebase_path(_typemap_stamp_filename, root_build_dir),
+      ]
+    }
+
+    action(type_mappings_target_name) {
+      allow_remote = true
+      inputs =
+          mojom_generator_sources + jinja2_sources + [ _typemap_stamp_filename ]
+      outputs = [ type_mappings_path ]
+      script = "$mojom_generator_root/generate_type_mappings.py"
+      deps = [ ":$_typemap_validator_target_name" ]
+      args = [
+        "--output",
+        rebase_path(type_mappings_path, root_build_dir),
+      ]
+
+      sources = []
+      foreach(d, all_deps) {
+        name = get_label_info(d, "label_no_toolchain")
+        toolchain = get_label_info(d, "toolchain")
+        dependency_output = "${name}${variant_suffix}__type_mappings"
+        dependency_target = "${dependency_output}(${toolchain})"
+        deps += [ dependency_target ]
+        dependency_output_dir =
+            get_label_info(dependency_output, "target_gen_dir")
+        dependency_name = get_label_info(dependency_output, "name")
+        dependency_path = "$dependency_output_dir/${dependency_name}"
+        sources += [ dependency_path ]
+        args += [
+          "--dependency",
+          rebase_path(dependency_path, root_build_dir),
+        ]
+      }
+
+      # Newer GN-based typemaps are aggregated into a single config.
+      inputs += [ _typemap_config_filename ]
+      args += [
+        "--cpp-typemap-config",
+        rebase_path(_typemap_config_filename, root_build_dir),
+      ]
+    }
+
+    group("${target_name}${variant_suffix}_headers") {
+      public_deps = []
+      if (sources_list != []) {
+        public_deps += [
+          ":$generator_cpp_message_ids_target_name",
+          ":$generator_shared_target_name",
+          ":$generator_target_name",
+        ]
+      }
+      foreach(d, all_deps) {
+        full_name = get_label_info("$d", "label_no_toolchain")
+        public_deps += [ "${full_name}${variant_suffix}_headers" ]
+      }
+      if (defined(bindings_configuration.for_blink) &&
+          bindings_configuration.for_blink) {
+        public_deps += [ "//mojo/public/cpp/bindings:wtf_support" ]
+      }
+    }
+
+    js_data_deps_target_name = target_name + "_js_data_deps"
+    not_needed([ "js_data_deps_target_name" ])
+
+    if (!force_source_set && defined(invoker.component_macro_prefix)) {
+      sources_target_type = "component"
+    } else {
+      sources_target_type = "source_set"
+    }
+
+    output_target_name = "${target_name}${variant_suffix}"
+    if (proxy_target != "") {
+      group(output_target_name) {
+        public_deps = [ proxy_target ]
+        visibility = output_visibility
+        if (defined(invoker.testonly)) {
+          testonly = invoker.testonly
+        }
+      }
+      sources_target_name = "${output_target_name}_cpp_sources"
+    } else {
+      sources_target_name = output_target_name
+    }
+
+    target(sources_target_type, sources_target_name) {
+      if (defined(output_name_override)) {
+        output_name = output_name_override
+      }
+      visibility = output_visibility + [
+                     ":$output_target_name",
+                     ":${target_name}_mojolpm",
+                   ]
+      if (defined(invoker.testonly)) {
+        testonly = invoker.testonly
+      }
+      defines = export_defines
+      configs += [ "//build/config/compiler:wexit_time_destructors" ]
+      configs += extra_configs
+      if (output_file_base_paths != []) {
+        sources = []
+        foreach(base_path, output_file_base_paths) {
+          foreach(suffix, generator_cpp_output_suffixes) {
+            sources += [ "$root_gen_dir/${base_path}$suffix" ]
+          }
+        }
+      }
+      deps = [
+        ":$generator_cpp_message_ids_target_name",
+        "//mojo/public/cpp/bindings:struct_traits",
+        "//mojo/public/interfaces/bindings:bindings_headers",
+      ]
+      public_deps = [
+        ":$shared_cpp_library_target_name",
+        "//base",
+      ]
+      if (require_full_cpp_deps) {
+        public_deps += [ "//mojo/public/cpp/bindings" ]
+      } else {
+        public_deps += [ "//mojo/public/cpp/bindings:bindings_base" ]
+      }
+
+      if (sources_list != []) {
+        public_deps += [ ":$generator_target_name" ]
+      }
+      foreach(d, mojom_cpp_deps) {
+        # Resolve the name, so that a target //mojo/something becomes
+        # //mojo/something:something and we can append variant_suffix to
+        # get the cpp dependency name.
+        full_name = get_label_info(d, "label_no_toolchain")
+        public_deps += [ "${full_name}${variant_suffix}" ]
+      }
+      foreach(d, cpp_source_deps) {
+        full_name = get_label_info(d, "label_no_toolchain")
+        public_deps += [
+          "${full_name}${variant_suffix}__has_cpp_proxy",
+          "${full_name}${variant_suffix}_cpp_sources",
+        ]
+      }
+      if (defined(bindings_configuration.for_blink) &&
+          bindings_configuration.for_blink) {
+        if (defined(invoker.overridden_deps_blink)) {
+          foreach(d, invoker.overridden_deps_blink) {
+            # Resolve the name, so that a target //mojo/something becomes
+            # //mojo/something:something and we can append variant_suffix
+            # to get the cpp dependency name.
+            full_name = get_label_info("$d", "label_no_toolchain")
+            public_deps -= [ "${full_name}${variant_suffix}" ]
+          }
+          public_deps += invoker.component_deps_blink
+        }
+        if (defined(invoker.check_includes_blink)) {
+          check_includes = invoker.check_includes_blink
+        }
+      } else {
+        if (defined(invoker.check_includes_blink)) {
+          not_needed(invoker, [ "check_includes_blink" ])
+        }
+        if (defined(invoker.overridden_deps)) {
+          foreach(d, invoker.overridden_deps) {
+            # Resolve the name, so that a target //mojo/something becomes
+            # //mojo/something:something and we can append variant_suffix
+            # to get the cpp dependency name.
+            full_name = get_label_info("$d", "label_no_toolchain")
+            public_deps -= [ "${full_name}${variant_suffix}" ]
+          }
+          public_deps += invoker.component_deps
+        }
+      }
+      foreach(config, cpp_typemap_configs) {
+        if (defined(config.traits_sources)) {
+          sources += config.traits_sources
+        }
+        if (defined(config.traits_deps)) {
+          deps += config.traits_deps
+        }
+        if (defined(config.traits_public_deps)) {
+          public_deps += config.traits_public_deps
+        }
+      }
+      if (defined(bindings_configuration.for_blink) &&
+          bindings_configuration.for_blink) {
+        public_deps += [ "//mojo/public/cpp/bindings:wtf_support" ]
+      }
+    }
+
+    if (generate_mojolpm_fuzzing && !defined(variant)) {
+      # This block contains the C++ targets for the MojoLPM fuzzer, we need to
+      # do this here so that we can use the typemap configuration for the
+      # empty-variant Mojo target.
+
+      mojolpm_target_name = "${target_name}_mojolpm"
+      mojolpm_generator_target_name = "${target_name}__generator"
+      source_set(mojolpm_target_name) {
+        # There are still a few missing header dependencies between mojo targets
+        # with typemaps and the dependencies of their typemap headers. It would
+        # be good to enable include checking for these in the future though.
+        check_includes = false
+        testonly = true
+        if (defined(invoker.sources)) {
+          # Split the input into generated and non-generated source files. They
+          # need to be processed separately.
+          gen_dir_path_wildcard = get_path_info("//", "gen_dir") + "/*"
+          non_gen_sources =
+              filter_exclude(invoker.sources, [ gen_dir_path_wildcard ])
+          gen_sources =
+              filter_include(invoker.sources, [ gen_dir_path_wildcard ])
+          sources = process_file_template(
+                  non_gen_sources,
+                  [
+                    "{{source_gen_dir}}/{{source_file_part}}-mojolpm.cc",
+                    "{{source_gen_dir}}/{{source_file_part}}-mojolpm.h",
+                  ])
+          sources += process_file_template(
+                  gen_sources,
+                  [
+                    "{{source_dir}}/{{source_file_part}}-mojolpm.cc",
+                    "{{source_dir}}/{{source_file_part}}-mojolpm.h",
+                  ])
+          deps = [ ":$output_target_name" ]
+        } else {
+          sources = []
+          deps = []
+        }
+
+        public_deps = [
+          ":$generator_shared_target_name",
+
+          # NB: hardcoded dependency on the no-variant variant generator, since
+          # mojolpm only uses the no-variant type.
+          ":$mojolpm_generator_target_name",
+          ":$mojolpm_proto_target_name",
+          "//base",
+          "//mojo/public/tools/fuzzers:mojolpm",
+        ]
+
+        foreach(d, all_deps) {
+          # Resolve the name, so that a target //mojo/something becomes
+          # //mojo/something:something and we can append variant_suffix to
+          # get the cpp dependency name.
+          full_name = get_label_info("$d", "label_no_toolchain")
+          public_deps += [ "${full_name}_mojolpm" ]
+        }
+
+        foreach(config, cpp_typemap_configs) {
+          if (defined(config.traits_deps)) {
+            deps += config.traits_deps
+          }
+          if (defined(config.traits_public_deps)) {
+            public_deps += config.traits_public_deps
+          }
+        }
+      }
+    }
+
+    if (generate_java && is_android) {
+      import("//build/config/android/rules.gni")
+
+      java_generator_target_name = target_name + "_java__generator"
+      if (sources_list != []) {
+        action(java_generator_target_name) {
+          script = mojom_generator_script
+          inputs = mojom_generator_sources + jinja2_sources
+          sources = sources_list
+          deps = [
+            ":$parser_target_name",
+            ":$type_mappings_target_name",
+            "//mojo/public/tools/bindings:precompile_templates",
+          ]
+          outputs = []
+          args = common_generator_args
+          filelist = []
+          foreach(source, sources_list) {
+            filelist += [ rebase_path(source, root_build_dir) ]
+          }
+          foreach(base_path, output_file_base_paths) {
+            outputs += [ "$root_gen_dir/$base_path.srcjar" ]
+          }
+
+          response_file_contents = filelist
+
+          args += [
+            "--filelist={{response_file_name}}",
+            "-g",
+            "java",
+          ]
+
+          if (!defined(invoker.scramble_message_ids) ||
+              invoker.scramble_message_ids) {
+            inputs += message_scrambling_inputs
+            args += message_scrambling_args
+          }
+        }
+      } else {
+        group(java_generator_target_name) {
+        }
+      }
+
+      java_srcjar_target_name = target_name + "_java_sources"
+
+      action(java_srcjar_target_name) {
+        script = "//build/android/gyp/zip.py"
+        inputs = []
+        if (output_file_base_paths != []) {
+          foreach(base_path, output_file_base_paths) {
+            inputs += [ "$root_gen_dir/${base_path}.srcjar" ]
+          }
+        }
+        output = "$target_gen_dir/$target_name.srcjar"
+        outputs = [ output ]
+        rebase_inputs = rebase_path(inputs, root_build_dir)
+        rebase_output = rebase_path(output, root_build_dir)
+        args = [
+          "--input-zips=$rebase_inputs",
+          "--output=$rebase_output",
+        ]
+        deps = []
+        if (sources_list != []) {
+          deps = [ ":$java_generator_target_name" ]
+        }
+      }
+
+      java_target_name = target_name + "_java"
+      android_library(java_target_name) {
+        forward_variables_from(invoker, [ "enable_bytecode_checks" ])
+        deps = [
+          "//mojo/public/java:bindings_java",
+          "//mojo/public/java:system_java",
+          "//third_party/androidx:androidx_annotation_annotation_java",
+        ]
+
+        # Disable warnings/checks on these generated files.
+        chromium_code = false
+
+        foreach(d, all_deps) {
+          # Resolve the name, so that a target //mojo/something becomes
+          # //mojo/something:something and we can append "_java" to get the java
+          # dependency name.
+          full_name = get_label_info(d, "label_no_toolchain")
+          deps += [ "${full_name}_java" ]
+        }
+
+        srcjar_deps = [ ":$java_srcjar_target_name" ]
+      }
+    }
+  }
+
+  if (defined(invoker.generate_webui_js_bindings)) {
+    assert(is_chromeos_ash,
+           "generate_webui_js_bindings can only be used on ChromeOS Ash")
+    assert(invoker.generate_webui_js_bindings,
+           "generate_webui_js_bindings should be set to true or removed")
+  }
+
+  use_typescript_for_target = defined(invoker.webui_module_path) &&
+                              !defined(invoker.generate_webui_js_bindings)
+
+  generate_legacy_js = !use_typescript_for_target ||
+                       (defined(invoker.generate_legacy_js_bindings) &&
+                        invoker.generate_legacy_js_bindings)
+
+  if (!use_typescript_for_target &&
+      defined(invoker.generate_legacy_js_bindings)) {
+    not_needed(invoker, [ "generate_legacy_js_bindings" ])
+  }
+
+  # Targets needed by both TS and JS bindings targets. These are needed
+  # unconditionally for JS bindings targets, and are needed for TS bindings
+  # targets when generate_legacy_js_bindings is true. This option is provided
+  # since the legacy bindings are needed by Blink tests and non-Chromium users,
+  # which are not expected to migrate to modules or TypeScript.
+  if (generate_legacy_js && (generate_js_fuzzing ||
+                             !defined(invoker.cpp_only) || !invoker.cpp_only)) {
+    if (sources_list != []) {
+      generator_js_target_name = "${target_name}_js__generator"
+
+      action(generator_js_target_name) {
+        script = mojom_generator_script
+        inputs = mojom_generator_sources + jinja2_sources
+        sources = sources_list
+        deps = [
+          ":$parser_target_name",
+          "//mojo/public/tools/bindings:precompile_templates",
+        ]
+        if (defined(invoker.parser_deps)) {
+          deps += invoker.parser_deps
+        }
+        outputs = []
+        args = common_generator_args
+        filelist = []
+        foreach(source, sources_list) {
+          filelist += [ rebase_path(source, root_build_dir) ]
+        }
+        foreach(base_path, output_file_base_paths) {
+          outputs += [
+            "$root_gen_dir/$base_path.js",
+            "$root_gen_dir/$base_path.m.js",
+            "$root_gen_dir/$base_path-lite.js",
+            "$root_gen_dir/$base_path-lite-for-compile.js",
+          ]
+
+          if (defined(invoker.webui_module_path) &&
+              !use_typescript_for_target) {
+            outputs += [ "$root_gen_dir/mojom-webui/$base_path-webui.js" ]
+          }
+        }
+
+        response_file_contents = filelist
+
+        args += [
+          "--filelist={{response_file_name}}",
+          "-g",
+          "javascript",
+        ]
+
+        if (defined(invoker.js_generate_struct_deserializers) &&
+            invoker.js_generate_struct_deserializers) {
+          args += [ "--js_generate_struct_deserializers" ]
+        }
+
+        if (!defined(invoker.scramble_message_ids) ||
+            invoker.scramble_message_ids) {
+          inputs += message_scrambling_inputs
+          args += message_scrambling_args
+        }
+
+        if (generate_js_fuzzing) {
+          args += [ "--generate_fuzzing" ]
+        }
+      }
+    }
+
+    js_target_name = target_name + "_js"
+    group(js_target_name) {
+      public_deps = []
+      if (sources_list != []) {
+        public_deps += [ ":$generator_js_target_name" ]
+      }
+
+      foreach(d, all_deps) {
+        full_name = get_label_info(d, "label_no_toolchain")
+        public_deps += [ "${full_name}_js" ]
+      }
+    }
+
+    group(js_data_deps_target_name) {
+      deps = []
+      if (sources_list != []) {
+        data = []
+        foreach(base_path, output_file_base_paths) {
+          data += [
+            "$root_gen_dir/${base_path}.js",
+            "$root_gen_dir/${base_path}.m.js",
+            "$root_gen_dir/${base_path}-lite.js",
+          ]
+        }
+        deps += [ ":$generator_js_target_name" ]
+      }
+
+      if (defined(invoker.disallow_native_types) &&
+          invoker.disallow_native_types) {
+        data_deps = []
+      } else {
+        data_deps = [ "//mojo/public/js:bindings_module" ]
+      }
+      foreach(d, all_deps) {
+        full_name = get_label_info(d, "label_no_toolchain")
+        data_deps += [ "${full_name}_js_data_deps" ]
+      }
+    }
+  }
+
+  # js_library() closure compiler targets, primarily used on ChromeOS. Only
+  # generate these targets if the mojom target is not C++ only and is not using
+  # TypeScript.
+  if (generate_mojom_closure_libraries &&
+      (!defined(invoker.cpp_only) || !invoker.cpp_only) && generate_legacy_js) {
+    js_library_for_compile_target_name = "${target_name}_js_library_for_compile"
+    if (sources_list != []) {
+      js_library(js_library_for_compile_target_name) {
+        extra_public_deps = [ ":$generator_js_target_name" ]
+        sources = []
+        foreach(base_path, output_file_base_paths) {
+          sources += [ "$root_gen_dir/${base_path}-lite-for-compile.js" ]
+        }
+        externs_list = [
+          "${externs_path}/mojo_core.js",
+          "${externs_path}/pending.js",
+        ]
+        deps = []
+        if (!defined(invoker.disallow_native_types)) {
+          deps += [ "//mojo/public/js:bindings_lite_sources" ]
+        }
+        foreach(d, all_deps) {
+          full_name = get_label_info(d, "label_no_toolchain")
+          deps += [ "${full_name}_js_library_for_compile" ]
+        }
+      }
+    } else {
+      group(js_library_for_compile_target_name) {
+      }
+    }
+
+    # WebUI specific closure targets, not needed by targets that are generating
+    # TypeScript WebUI bindings or by legacy-only targets.
+    if (defined(invoker.webui_module_path) && !use_typescript_for_target) {
+      webui_js_target_name = "${target_name}_webui_js"
+      if (sources_list != []) {
+        js_library(webui_js_target_name) {
+          extra_public_deps = [ ":$generator_js_target_name" ]
+          sources = []
+          foreach(base_path, output_file_base_paths) {
+            sources += [ "$root_gen_dir/mojom-webui/${base_path}-webui.js" ]
+          }
+          externs_list = [
+            "${externs_path}/mojo_core.js",
+            "${externs_path}/pending.js",
+          ]
+          if (defined(invoker.disallow_native_types) &&
+              invoker.disallow_native_types) {
+            deps = []
+          } else {
+            deps = [ "//mojo/public/js:bindings_uncompiled" ]
+          }
+          foreach(d, all_deps) {
+            full_name = get_label_info(d, "label_no_toolchain")
+            deps += [ "${full_name}_webui_js" ]
+          }
+        }
+      } else {
+        group(webui_js_target_name) {
+        }
+      }
+
+      webui_grdp_target_name = "${target_name}_webui_grdp"
+      out_grd = "$target_gen_dir/${target_name}_webui_resources.grdp"
+      grd_prefix = "${target_name}_webui"
+      generate_grd(webui_grdp_target_name) {
+        grd_prefix = grd_prefix
+        out_grd = out_grd
+
+        deps = [ ":$webui_js_target_name" ]
+
+        input_files = []
+        foreach(base_path, output_file_base_paths) {
+          input_files += [ "${base_path}-webui.js" ]
+        }
+
+        input_files_base_dir =
+            rebase_path("$root_gen_dir/mojom-webui", "$root_build_dir")
+      }
+    }
+  }
+  if ((generate_js_fuzzing || !defined(invoker.cpp_only) ||
+       !invoker.cpp_only) && use_typescript_for_target) {
+    if (sources_list != []) {
+      source_filelist = []
+      foreach(source, sources_list) {
+        source_filelist += [ rebase_path(source, root_build_dir) ]
+      }
+
+      # Generate Typescript bindings.
+      generator_ts_target_name = "${target_name}_ts__generator"
+
+      action(generator_ts_target_name) {
+        script = mojom_generator_script
+        inputs = mojom_generator_sources + jinja2_sources
+        sources = sources_list
+        deps = [
+          ":$parser_target_name",
+          "//mojo/public/tools/bindings:precompile_templates",
+        ]
+
+        outputs = []
+        foreach(base_path, output_file_base_paths) {
+          outputs += [ "$root_gen_dir/$base_path-webui.ts" ]
+        }
+        args = common_generator_args
+        response_file_contents = source_filelist
+
+        args += [
+          "--filelist={{response_file_name}}",
+          "-g",
+          "typescript",
+        ]
+
+        if (!defined(invoker.scramble_message_ids) ||
+            invoker.scramble_message_ids) {
+          inputs += message_scrambling_inputs
+          args += message_scrambling_args
+        }
+
+        if (defined(invoker.js_generate_struct_deserializers) &&
+            invoker.js_generate_struct_deserializers) {
+          args += [ "--js_generate_struct_deserializers" ]
+        }
+
+        # TODO(crbug.com/1007587): Support scramble_message_ids if above is
+        # insufficient.
+        # TODO(crbug.com/1007591): Support generate_fuzzing.
+      }
+    }
+  }
+}
+
+# A helper for the mojom() template above when component libraries are desired
+# for generated C++ bindings units. Supports all the same arguments as mojom()
+# except for the optional |component_output_prefix| and |component_macro_prefix|
+# arguments. These are instead shortened to |output_prefix| and |macro_prefix|
+# and are *required*.
+template("mojom_component") {
+  assert(defined(invoker.output_prefix) && defined(invoker.macro_prefix))
+
+  mojom(target_name) {
+    forward_variables_from(invoker,
+                           "*",
+                           [
+                             "output_prefix",
+                             "macro_prefix",
+                           ])
+    component_output_prefix = invoker.output_prefix
+    component_macro_prefix = invoker.macro_prefix
+  }
+}
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py b/utils/codegen/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py
new file mode 100755
index 00000000..8c641c2a
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py
@@ -0,0 +1,424 @@
+#!/usr/bin/env python
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""The frontend for the Mojo bindings system."""
+
+from __future__ import print_function
+
+import argparse
+
+import hashlib
+import importlib
+import json
+import os
+import pprint
+import re
+import struct
+import sys
+
+# Disable lint check for finding modules:
+# pylint: disable=F0401
+
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, tail = os.path.split(path)
+    assert tail
+    if tail == dirname:
+      return path
+
+
+sys.path.insert(
+    0,
+    os.path.join(
+        os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "mojom"))
+
+from mojom.error import Error
+import mojom.fileutil as fileutil
+from mojom.generate.module import Module
+from mojom.generate import template_expander
+from mojom.generate import translate
+from mojom.generate.generator import WriteFile
+
+sys.path.append(
+    os.path.join(_GetDirAbove("mojo"), "tools", "diagnosis"))
+import crbug_1001171
+
+
+_BUILTIN_GENERATORS = {
+    "c++": "mojom_cpp_generator",
+    "javascript": "mojom_js_generator",
+    "java": "mojom_java_generator",
+    "mojolpm": "mojom_mojolpm_generator",
+    "typescript": "mojom_ts_generator",
+}
+
+_BUILTIN_CHECKS = {
+    "attributes": "mojom_attributes_check",
+    "definitions": "mojom_definitions_check",
+    "features": "mojom_interface_feature_check",
+    "restrictions": "mojom_restrictions_check",
+}
+
+
+def LoadGenerators(generators_string):
+  if not generators_string:
+    return {}  # No generators.
+
+  generators = {}
+  for generator_name in [s.strip() for s in generators_string.split(",")]:
+    language = generator_name.lower()
+    if language not in _BUILTIN_GENERATORS:
+      print("Unknown generator name %s" % generator_name)
+      sys.exit(1)
+    generator_module = importlib.import_module(
+        "generators.%s" % _BUILTIN_GENERATORS[language])
+    generators[language] = generator_module
+  return generators
+
+
+def LoadChecks(checks_string):
+  if not checks_string:
+    return {}  # No checks.
+
+  checks = {}
+  for check_name in [s.strip() for s in checks_string.split(",")]:
+    check = check_name.lower()
+    if check not in _BUILTIN_CHECKS:
+      print("Unknown check name %s" % check_name)
+      sys.exit(1)
+    check_module = importlib.import_module("checks.%s" % _BUILTIN_CHECKS[check])
+    checks[check] = check_module
+  return checks
+
+
+def MakeImportStackMessage(imported_filename_stack):
+  """Make a (human-readable) message listing a chain of imports. (Returned
+  string begins with a newline (if nonempty) and does not end with one.)"""
+  return ''.join(
+      reversed(["\n  %s was imported by %s" % (a, b) for (a, b) in \
+                    zip(imported_filename_stack[1:], imported_filename_stack)]))
+
+
+class RelativePath:
+  """Represents a path relative to the source tree or generated output dir."""
+
+  def __init__(self, path, source_root, output_dir):
+    self.path = path
+    if path.startswith(source_root):
+      self.root = source_root
+    elif path.startswith(output_dir):
+      self.root = output_dir
+    else:
+      raise Exception("Invalid input path %s" % path)
+
+  def relative_path(self):
+    return os.path.relpath(
+        os.path.abspath(self.path), os.path.abspath(self.root))
+
+
+def _GetModulePath(path, output_dir):
+  return os.path.join(output_dir, path.relative_path() + '-module')
+
+
+def ScrambleMethodOrdinals(interfaces, salt):
+  already_generated = set()
+  for interface in interfaces:
+    i = 0
+    already_generated.clear()
+    for method in interface.methods:
+      if method.explicit_ordinal is not None:
+        continue
+      while True:
+        i = i + 1
+        if i == 1000000:
+          raise Exception("Could not generate %d method ordinals for %s" %
+              (len(interface.methods), interface.mojom_name))
+        # Generate a scrambled method.ordinal value. The algorithm doesn't have
+        # to be very strong, cryptographically. It just needs to be non-trivial
+        # to guess the results without the secret salt, in order to make it
+        # harder for a compromised process to send fake Mojo messages.
+        sha256 = hashlib.sha256(salt)
+        sha256.update(interface.mojom_name.encode('utf-8'))
+        sha256.update(str(i).encode('utf-8'))
+        # Take the first 4 bytes as a little-endian uint32.
+        ordinal = struct.unpack('<L', sha256.digest()[:4])[0]
+        # Trim to 31 bits, so it always fits into a Java (signed) int.
+        ordinal = ordinal & 0x7fffffff
+        if ordinal in already_generated:
+          continue
+        already_generated.add(ordinal)
+        method.ordinal = ordinal
+        method.ordinal_comment = (
+            'The %s value is based on sha256(salt + "%s%d").' %
+            (ordinal, interface.mojom_name, i))
+        break
+
+
+def ReadFileContents(filename):
+  with open(filename, 'rb') as f:
+    return f.read()
+
+
+class MojomProcessor:
+  """Takes parsed mojom modules and generates language bindings from them.
+
+  Attributes:
+    _processed_files: {Dict[str, mojom.generate.module.Module]} Mapping from
+        relative mojom filename paths to the module AST for that mojom file.
+  """
+  def __init__(self, should_generate):
+    self._should_generate = should_generate
+    self._processed_files = {}
+    self._typemap = {}
+
+  def LoadTypemaps(self, typemaps):
+    # Support some very simple single-line comments in typemap JSON.
+    comment_expr = r"^\s*//.*$"
+    def no_comments(line):
+      return not re.match(comment_expr, line)
+    for filename in typemaps:
+      with open(filename) as f:
+        typemaps = json.loads("".join(filter(no_comments, f.readlines())))
+        for language, typemap in typemaps.items():
+          language_map = self._typemap.get(language, {})
+          language_map.update(typemap)
+          self._typemap[language] = language_map
+    if 'c++' in self._typemap:
+      self._typemap['mojolpm'] = self._typemap['c++']
+
+  def _GenerateModule(self, args, remaining_args, check_modules,
+                      generator_modules, rel_filename, imported_filename_stack):
+    # Return the already-generated module.
+    if rel_filename.path in self._processed_files:
+      return self._processed_files[rel_filename.path]
+
+    if rel_filename.path in imported_filename_stack:
+      print("%s: Error: Circular dependency" % rel_filename.path + \
+          MakeImportStackMessage(imported_filename_stack + [rel_filename.path]))
+      sys.exit(1)
+
+    module_path = _GetModulePath(rel_filename, args.output_dir)
+    with open(module_path, 'rb') as f:
+      module = Module.Load(f)
+
+    if args.scrambled_message_id_salt_paths:
+      salt = b''.join(
+          map(ReadFileContents, args.scrambled_message_id_salt_paths))
+      ScrambleMethodOrdinals(module.interfaces, salt)
+
+    if self._should_generate(rel_filename.path):
+      # Run checks on module first.
+      for check_module in check_modules.values():
+        checker = check_module.Check(module)
+        checker.CheckModule()
+      # Then run generation.
+      for language, generator_module in generator_modules.items():
+        generator = generator_module.Generator(
+            module, args.output_dir, typemap=self._typemap.get(language, {}),
+            variant=args.variant, bytecode_path=args.bytecode_path,
+            for_blink=args.for_blink,
+            js_generate_struct_deserializers=\
+                    args.js_generate_struct_deserializers,
+            export_attribute=args.export_attribute,
+            export_header=args.export_header,
+            generate_non_variant_code=args.generate_non_variant_code,
+            support_lazy_serialization=args.support_lazy_serialization,
+            disallow_native_types=args.disallow_native_types,
+            disallow_interfaces=args.disallow_interfaces,
+            generate_message_ids=args.generate_message_ids,
+            generate_fuzzing=args.generate_fuzzing,
+            enable_kythe_annotations=args.enable_kythe_annotations,
+            extra_cpp_template_paths=args.extra_cpp_template_paths,
+            generate_extra_cpp_only=args.generate_extra_cpp_only)
+        filtered_args = []
+        if hasattr(generator_module, 'GENERATOR_PREFIX'):
+          prefix = '--' + generator_module.GENERATOR_PREFIX + '_'
+          filtered_args = [arg for arg in remaining_args
+                           if arg.startswith(prefix)]
+        generator.GenerateFiles(filtered_args)
+
+    # Save result.
+    self._processed_files[rel_filename.path] = module
+    return module
+
+
+def _Generate(args, remaining_args):
+  if args.variant == "none":
+    args.variant = None
+
+  for idx, import_dir in enumerate(args.import_directories):
+    tokens = import_dir.split(":")
+    if len(tokens) >= 2:
+      args.import_directories[idx] = RelativePath(tokens[0], tokens[1],
+                                                  args.output_dir)
+    else:
+      args.import_directories[idx] = RelativePath(tokens[0], args.depth,
+                                                  args.output_dir)
+  generator_modules = LoadGenerators(args.generators_string)
+  check_modules = LoadChecks(args.checks_string)
+
+  fileutil.EnsureDirectoryExists(args.output_dir)
+
+  processor = MojomProcessor(lambda filename: filename in args.filename)
+  processor.LoadTypemaps(set(args.typemaps))
+
+  if args.filelist:
+    with open(args.filelist) as f:
+      args.filename.extend(f.read().split())
+
+  for filename in args.filename:
+    processor._GenerateModule(
+        args, remaining_args, check_modules, generator_modules,
+        RelativePath(filename, args.depth, args.output_dir), [])
+
+  return 0
+
+
+def _Precompile(args, _):
+  generator_modules = LoadGenerators(",".join(_BUILTIN_GENERATORS.keys()))
+
+  template_expander.PrecompileTemplates(generator_modules, args.output_dir)
+  return 0
+
+
+def main():
+  parser = argparse.ArgumentParser(
+      description="Generate bindings from mojom files.")
+  parser.add_argument("--use_bundled_pylibs", action="store_true",
+                      help="use Python modules bundled in the SDK")
+  parser.add_argument(
+      "-o",
+      "--output_dir",
+      dest="output_dir",
+      default=".",
+      help="output directory for generated files")
+
+  subparsers = parser.add_subparsers()
+
+  generate_parser = subparsers.add_parser(
+      "generate", description="Generate bindings from mojom files.")
+  generate_parser.add_argument("filename", nargs="*",
+                               help="mojom input file")
+  generate_parser.add_argument("--filelist", help="mojom input file list")
+  generate_parser.add_argument("-d", "--depth", dest="depth", default=".",
+                               help="depth from source root")
+  generate_parser.add_argument("-g",
+                               "--generators",
+                               dest="generators_string",
+                               metavar="GENERATORS",
+                               default="c++,javascript,java,mojolpm",
+                               help="comma-separated list of generators")
+  generate_parser.add_argument("-c",
+                               "--checks",
+                               dest="checks_string",
+                               metavar="CHECKS",
+                               default=",".join(_BUILTIN_CHECKS.keys()),
+                               help="comma-separated list of checks")
+  generate_parser.add_argument(
+      "--gen_dir", dest="gen_directories", action="append", metavar="directory",
+      default=[], help="add a directory to be searched for the syntax trees.")
+  generate_parser.add_argument(
+      "-I", dest="import_directories", action="append", metavar="directory",
+      default=[],
+      help="add a directory to be searched for import files. The depth from "
+           "source root can be specified for each import by appending it after "
+           "a colon")
+  generate_parser.add_argument("--typemap", action="append", metavar="TYPEMAP",
+                               default=[], dest="typemaps",
+                               help="apply TYPEMAP to generated output")
+  generate_parser.add_argument("--variant", dest="variant", default=None,
+                               help="output a named variant of the bindings")
+  generate_parser.add_argument(
+      "--bytecode_path", required=True, help=(
+          "the path from which to load template bytecode; to generate template "
+          "bytecode, run %s precompile BYTECODE_PATH" % os.path.basename(
+              sys.argv[0])))
+  generate_parser.add_argument("--for_blink", action="store_true",
+                               help="Use WTF types as generated types for mojo "
+                               "string/array/map.")
+  generate_parser.add_argument(
+      "--js_generate_struct_deserializers", action="store_true",
+      help="Generate javascript deserialize methods for structs in "
+      "mojom-lite.js file")
+  generate_parser.add_argument(
+      "--export_attribute", default="",
+      help="Optional attribute to specify on class declaration to export it "
+      "for the component build.")
+  generate_parser.add_argument(
+      "--export_header", default="",
+      help="Optional header to include in the generated headers to support the "
+      "component build.")
+  generate_parser.add_argument(
+      "--generate_non_variant_code", action="store_true",
+      help="Generate code that is shared by different variants.")
+  generate_parser.add_argument(
+      "--scrambled_message_id_salt_path",
+      dest="scrambled_message_id_salt_paths",
+      help="If non-empty, the path to a file whose contents should be used as"
+      "a salt for generating scrambled message IDs. If this switch is specified"
+      "more than once, the contents of all salt files are concatenated to form"
+      "the salt value.", default=[], action="append")
+  generate_parser.add_argument(
+      "--support_lazy_serialization",
+      help="If set, generated bindings will serialize lazily when possible.",
+      action="store_true")
+  generate_parser.add_argument(
+      "--extra_cpp_template_paths",
+      dest="extra_cpp_template_paths",
+      action="append",
+      metavar="path_to_template",
+      default=[],
+      help="Provide a path to a new template (.tmpl) that is used to generate "
+      "additional C++ source/header files ")
+  generate_parser.add_argument(
+      "--generate_extra_cpp_only",
+      help="If set and extra_cpp_template_paths provided, will only generate"
+      "extra_cpp_template related C++ bindings",
+      action="store_true")
+  generate_parser.add_argument(
+      "--disallow_native_types",
+      help="Disallows the [Native] attribute to be specified on structs or "
+      "enums within the mojom file.", action="store_true")
+  generate_parser.add_argument(
+      "--disallow_interfaces",
+      help="Disallows interface definitions within the mojom file. It is an "
+      "error to specify this flag when processing a mojom file which defines "
+      "any interface.", action="store_true")
+  generate_parser.add_argument(
+      "--generate_message_ids",
+      help="Generates only the message IDs header for C++ bindings. Note that "
+      "this flag only matters if --generate_non_variant_code is also "
+      "specified.", action="store_true")
+  generate_parser.add_argument(
+      "--generate_fuzzing",
+      action="store_true",
+      help="Generates additional bindings for fuzzing in JS.")
+  generate_parser.add_argument(
+      "--enable_kythe_annotations",
+      action="store_true",
+      help="Adds annotations for kythe metadata generation.")
+
+  generate_parser.set_defaults(func=_Generate)
+
+  precompile_parser = subparsers.add_parser("precompile",
+      description="Precompile templates for the mojom bindings generator.")
+  precompile_parser.set_defaults(func=_Precompile)
+
+  args, remaining_args = parser.parse_known_args()
+  return args.func(args, remaining_args)
+
+
+if __name__ == "__main__":
+  with crbug_1001171.DumpStateOnLookupError():
+    ret = main()
+    # Exit without running GC, which can save multiple seconds due to the large
+    # number of object created. But flush is necessary as os._exit doesn't do
+    # that.
+    sys.stdout.flush()
+    sys.stderr.flush()
+    os._exit(ret)
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py b/utils/codegen/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py
new file mode 100644
index 00000000..761922b6
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py
@@ -0,0 +1,62 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+from mojom_bindings_generator import MakeImportStackMessage
+from mojom_bindings_generator import ScrambleMethodOrdinals
+
+
+class FakeIface:
+  def __init__(self):
+    self.mojom_name = None
+    self.methods = None
+
+
+class FakeMethod:
+  def __init__(self, explicit_ordinal=None):
+    self.explicit_ordinal = explicit_ordinal
+    self.ordinal = explicit_ordinal
+    self.ordinal_comment = None
+
+
+class MojoBindingsGeneratorTest(unittest.TestCase):
+  """Tests mojo_bindings_generator."""
+
+  def testMakeImportStackMessage(self):
+    """Tests MakeImportStackMessage()."""
+    self.assertEqual(MakeImportStackMessage(["x"]), "")
+    self.assertEqual(MakeImportStackMessage(["x", "y"]),
+                     "\n  y was imported by x")
+    self.assertEqual(MakeImportStackMessage(["x", "y", "z"]),
+                     "\n  z was imported by y\n  y was imported by x")
+
+  def testScrambleMethodOrdinals(self):
+    """Tests ScrambleMethodOrdinals()."""
+    interface = FakeIface()
+    interface.mojom_name = 'RendererConfiguration'
+    interface.methods = [
+        FakeMethod(),
+        FakeMethod(),
+        FakeMethod(),
+        FakeMethod(explicit_ordinal=42)
+    ]
+    ScrambleMethodOrdinals([interface], "foo".encode('utf-8'))
+    # These next three values are hard-coded. If the generation algorithm
+    # changes from being based on sha256(seed + interface.name + str(i)) then
+    # these numbers will obviously need to change too.
+    #
+    # Note that hashlib.sha256('fooRendererConfiguration1').digest()[:4] is
+    # '\xa5\xbc\xf9\xca' and that hex(1257880741) = '0x4af9bca5'. The
+    # difference in 0x4a vs 0xca is because we only take 31 bits.
+    self.assertEqual(interface.methods[0].ordinal, 1257880741)
+    self.assertEqual(interface.methods[1].ordinal, 631133653)
+    self.assertEqual(interface.methods[2].ordinal, 549336076)
+
+    # Explicit method ordinals should not be scrambled.
+    self.assertEqual(interface.methods[3].ordinal, 42)
+
+
+if __name__ == "__main__":
+  unittest.main()
diff --git a/utils/codegen/ipc/mojo/public/tools/bindings/validate_typemap_config.py b/utils/codegen/ipc/mojo/public/tools/bindings/validate_typemap_config.py
new file mode 100755
index 00000000..6bb7a209
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/bindings/validate_typemap_config.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import argparse
+import json
+import os
+import re
+import sys
+
+
+def CheckCppTypemapConfigs(target_name, config_filename, out_filename):
+  _SUPPORTED_CONFIG_KEYS = set([
+      'types', 'traits_headers', 'traits_private_headers', 'traits_sources',
+      'traits_deps', 'traits_public_deps'
+  ])
+  _SUPPORTED_TYPE_KEYS = set([
+      'mojom', 'cpp', 'copyable_pass_by_value', 'force_serialize', 'hashable',
+      'move_only', 'nullable_is_same_type', 'forward_declaration',
+      'default_constructible'
+  ])
+  with open(config_filename, 'r') as f:
+    for config in json.load(f):
+      for key in config.keys():
+        if key not in _SUPPORTED_CONFIG_KEYS:
+          raise ValueError('Invalid typemap property "%s" when processing %s' %
+                           (key, target_name))
+
+      types = config.get('types')
+      if not types:
+        raise ValueError('Typemap for %s must specify at least one type to map'
+                         % target_name)
+
+      for entry in types:
+        for key in entry.keys():
+          if key not in _SUPPORTED_TYPE_KEYS:
+            raise IOError(
+                'Invalid type property "%s" in typemap for "%s" on target %s' %
+                (key, entry.get('mojom', '(unknown)'), target_name))
+
+  with open(out_filename, 'w') as f:
+    f.truncate(0)
+
+
+def main():
+  parser = argparse.ArgumentParser()
+  _, args = parser.parse_known_args()
+  if len(args) != 3:
+    print('Usage: validate_typemap_config.py target_name config_filename '
+          'stamp_filename')
+    sys.exit(1)
+
+  CheckCppTypemapConfigs(args[0], args[1], args[2])
+
+
+if __name__ == '__main__':
+  main()
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/BUILD.gn b/utils/codegen/ipc/mojo/public/tools/mojom/BUILD.gn
new file mode 100644
index 00000000..eafb95a1
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/BUILD.gn
@@ -0,0 +1,18 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+group("tests") {
+  data = [
+    "check_stable_mojom_compatibility_unittest.py",
+    "check_stable_mojom_compatibility.py",
+    "const_unittest.py",
+    "enum_unittest.py",
+    "feature_unittest.py",
+    "mojom_parser_test_case.py",
+    "mojom_parser_unittest.py",
+    "mojom_parser.py",
+    "stable_attribute_unittest.py",
+    "version_compatibility_unittest.py",
+  ]
+}
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/README.md b/utils/codegen/ipc/mojo/public/tools/mojom/README.md
new file mode 100644
index 00000000..e5d17ab0
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/README.md
@@ -0,0 +1,14 @@
+# The Mojom Parser
+
+The Mojom format is an interface definition language (IDL) for describing
+interprocess communication (IPC) messages and data types for use with the
+low-level cross-platform
+[Mojo IPC library](https://chromium.googlesource.com/chromium/src/+/main/mojo/public/c/system/README.md).
+
+This directory consists of a `mojom` Python module, its tests, and supporting
+command-line tools. The Python module implements the parser used by the
+command-line tools and exposes an API to help external bindings generators emit
+useful code from the parser's outputs.
+
+TODO(https://crbug.com/1060464): Fill out this documentation once the library
+and tools have stabilized.
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/check_stable_mojom_compatibility.py b/utils/codegen/ipc/mojo/public/tools/mojom/check_stable_mojom_compatibility.py
new file mode 100755
index 00000000..35cd1cfd
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/check_stable_mojom_compatibility.py
@@ -0,0 +1,204 @@
+#!/usr/bin/env python3
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Verifies backward-compatibility of mojom type changes.
+
+Given a set of pre- and post-diff mojom file contents, and a root directory
+for a project, this tool verifies that any changes to [Stable] mojom types are
+backward-compatible with the previous version.
+
+This can be used e.g. by a presubmit check to prevent developers from making
+breaking changes to stable mojoms."""
+
+import argparse
+import io
+import json
+import os
+import os.path
+import sys
+
+from mojom.generate import module
+from mojom.generate import translate
+from mojom.parse import parser
+
+# pylint: disable=raise-missing-from
+
+
+class ParseError(Exception):
+  pass
+
+
+def _ValidateDelta(root, delta):
+  """Parses all modified mojoms (including all transitive mojom dependencies,
+  even if unmodified) to perform backward-compatibility checks on any types
+  marked with the [Stable] attribute.
+
+  Note that unlike the normal build-time parser in mojom_parser.py, this does
+  not produce or rely on cached module translations, but instead parses the full
+  transitive closure of a mojom's input dependencies all at once.
+  """
+
+  translate.is_running_backwards_compatibility_check_hack = True
+
+  # First build a map of all files covered by the delta
+  affected_files = set()
+  old_files = {}
+  new_files = {}
+  for change in delta:
+    # TODO(crbug.com/953884): Use pathlib once we're migrated fully to Python 3.
+    filename = change['filename'].replace('\\', '/')
+    affected_files.add(filename)
+    if change['old']:
+      old_files[filename] = change['old']
+    if change['new']:
+      new_files[filename] = change['new']
+
+  # Parse and translate all mojoms relevant to the delta, including transitive
+  # imports that weren't modified.
+  unmodified_modules = {}
+
+  def parseMojom(mojom, file_overrides, override_modules):
+    if mojom in unmodified_modules or mojom in override_modules:
+      return
+
+    contents = file_overrides.get(mojom)
+    if contents:
+      modules = override_modules
+    else:
+      modules = unmodified_modules
+      with io.open(os.path.join(root, mojom), encoding='utf-8') as f:
+        contents = f.read()
+
+    try:
+      ast = parser.Parse(contents, mojom)
+    except Exception as e:
+      raise ParseError('encountered exception {0} while parsing {1}'.format(
+          e, mojom))
+
+    # Files which are generated at compile time can't be checked by this script
+    # (at the moment) since they may not exist in the output directory.
+    generated_files_to_skip = {
+        ('third_party/blink/public/mojom/runtime_feature_state/'
+         'runtime_feature.mojom'),
+        ('third_party/blink/public/mojom/origin_trial_feature/'
+         'origin_trial_feature.mojom'),
+    }
+
+    ast.import_list.items = [
+        x for x in ast.import_list.items
+        if x.import_filename not in generated_files_to_skip
+    ]
+
+    for imp in ast.import_list:
+      if (not file_overrides.get(imp.import_filename)
+          and not os.path.exists(os.path.join(root, imp.import_filename))):
+        # Speculatively construct a path prefix to locate the import_filename
+        mojom_path = os.path.dirname(os.path.normpath(mojom)).split(os.sep)
+        test_prefix = ''
+        for path_component in mojom_path:
+          test_prefix = os.path.join(test_prefix, path_component)
+          test_import_filename = os.path.join(test_prefix, imp.import_filename)
+          if os.path.exists(os.path.join(root, test_import_filename)):
+            imp.import_filename = test_import_filename
+            break
+      parseMojom(imp.import_filename, file_overrides, override_modules)
+
+    # Now that the transitive set of dependencies has been imported and parsed
+    # above, translate each mojom AST into a Module so that all types are fully
+    # defined and can be inspected.
+    all_modules = {}
+    all_modules.update(unmodified_modules)
+    all_modules.update(override_modules)
+    modules[mojom] = translate.OrderedModule(ast, mojom, all_modules)
+
+  old_modules = {}
+  for mojom in old_files:
+    parseMojom(mojom, old_files, old_modules)
+  new_modules = {}
+  for mojom in new_files:
+    parseMojom(mojom, new_files, new_modules)
+
+  # At this point we have a complete set of translated Modules from both the
+  # pre- and post-diff mojom contents. Now we can analyze backward-compatibility
+  # of the deltas.
+  #
+  # Note that for backward-compatibility checks we only care about types which
+  # were marked [Stable] before the diff. Types newly marked as [Stable] are not
+  # checked.
+  def collectTypes(modules):
+    types = {}
+    for m in modules.values():
+      for kinds in (m.enums, m.structs, m.unions, m.interfaces):
+        for kind in kinds:
+          types[kind.qualified_name] = kind
+    return types
+
+  old_types = collectTypes(old_modules)
+  new_types = collectTypes(new_modules)
+
+  # Collect any renamed types so they can be compared accordingly.
+  renamed_types = {}
+  for name, kind in new_types.items():
+    old_name = kind.attributes and kind.attributes.get('RenamedFrom')
+    if old_name:
+      renamed_types[old_name] = name
+
+  for qualified_name, kind in old_types.items():
+    if not kind.stable:
+      continue
+
+    new_name = renamed_types.get(qualified_name, qualified_name)
+    if new_name not in new_types:
+      raise Exception(
+          'Stable type %s appears to be deleted by this change. If it was '
+          'renamed, please add a [RenamedFrom] attribute to the new type. This '
+          'can be deleted by a subsequent change.' % qualified_name)
+
+    checker = module.BackwardCompatibilityChecker()
+    try:
+      if not checker.IsBackwardCompatible(new_types[new_name], kind):
+        raise Exception(
+            'Stable type %s appears to have changed in a way which '
+            'breaks backward-compatibility. Please fix!\n\nIf you '
+            'believe this assessment to be incorrect, please file a '
+            'Chromium bug against the "Internals>Mojo>Bindings" '
+            'component.' % qualified_name)
+    except Exception as e:
+      raise Exception(
+          'Stable type %s appears to have changed in a way which '
+          'breaks backward-compatibility: \n\n%s.\nPlease fix!\n\nIf you '
+          'believe this assessment to be incorrect, please file a '
+          'Chromium bug against the "Internals>Mojo>Bindings" '
+          'component.' % (qualified_name, e))
+
+
+def Run(command_line, delta=None):
+  """Runs the tool with the given command_line. Normally this will read the
+  change description from stdin as a JSON-encoded list, but tests may pass a
+  delta directly for convenience."""
+  arg_parser = argparse.ArgumentParser(
+      description='Verifies backward-compatibility of mojom type changes.',
+      epilog="""
+This tool reads a change description from stdin and verifies that all modified
+[Stable] mojom types will retain backward-compatibility. The change description
+must be a JSON-encoded list of objects, each with a "filename" key (path to a
+changed mojom file, relative to ROOT); an "old" key whose value is a string of
+the full file contents before the change, or null if the file is being added;
+and a "new" key whose value is a string of the full file contents after the
+change, or null if the file is being deleted.""")
+  arg_parser.add_argument(
+      '--src-root',
+      required=True,
+      action='store',
+      metavar='ROOT',
+      help='The root of the source tree in which the checked mojoms live.')
+
+  args, _ = arg_parser.parse_known_args(command_line)
+  if not delta:
+    delta = json.load(sys.stdin)
+  _ValidateDelta(args.src_root, delta)
+
+
+if __name__ == '__main__':
+  Run(sys.argv[1:])
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/check_stable_mojom_compatibility_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/check_stable_mojom_compatibility_unittest.py
new file mode 100755
index 00000000..06769c95
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/check_stable_mojom_compatibility_unittest.py
@@ -0,0 +1,339 @@
+#!/usr/bin/env python3
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import json
+import os
+import os.path
+import shutil
+import tempfile
+import unittest
+
+import check_stable_mojom_compatibility
+
+from mojom.generate import module
+
+
+class Change:
+  """Helper to clearly define a mojom file delta to be analyzed."""
+
+  def __init__(self, filename, old=None, new=None):
+    """If old is None, this is a file addition. If new is None, this is a file
+    deletion. Otherwise it's a file change."""
+    self.filename = filename
+    self.old = old
+    self.new = new
+
+
+class UnchangedFile(Change):
+  def __init__(self, filename, contents):
+    super().__init__(filename, old=contents, new=contents)
+
+
+class CheckStableMojomCompatibilityTest(unittest.TestCase):
+  """Tests covering the behavior of the compatibility checking tool. Note that
+  details of different compatibility checks and relevant failure modes are NOT
+  covered by these tests. Those are instead covered by unittests in
+  version_compatibility_unittest.py. Additionally, the tests which ensure a
+  given set of [Stable] mojom definitions are indeed plausibly stable (i.e. they
+  have no unstable dependencies) are covered by stable_attribute_unittest.py.
+
+  These tests cover higher-level concerns of the compatibility checking tool,
+  like file or symbol, renames, changes spread over multiple files, etc."""
+
+  def verifyBackwardCompatibility(self, changes):
+    """Helper for implementing assertBackwardCompatible and
+    assertNotBackwardCompatible"""
+
+    temp_dir = tempfile.mkdtemp()
+    for change in changes:
+      if change.old:
+        # Populate the old file on disk in our temporary fake source root
+        file_path = os.path.join(temp_dir, change.filename)
+        dir_path = os.path.dirname(file_path)
+        if not os.path.exists(dir_path):
+          os.makedirs(dir_path)
+        with open(file_path, 'w') as f:
+          f.write(change.old)
+
+    delta = []
+    for change in changes:
+      if change.old != change.new:
+        delta.append({
+            'filename': change.filename,
+            'old': change.old,
+            'new': change.new
+        })
+
+    try:
+      check_stable_mojom_compatibility.Run(['--src-root', temp_dir],
+                                           delta=delta)
+    finally:
+      shutil.rmtree(temp_dir)
+
+  def assertBackwardCompatible(self, changes):
+    self.verifyBackwardCompatibility(changes)
+
+  def assertNotBackwardCompatible(self, changes):
+    try:
+      self.verifyBackwardCompatibility(changes)
+    except Exception:
+      return
+
+    raise Exception('Change unexpectedly passed a backward-compatibility check')
+
+  def testBasicCompatibility(self):
+    """Minimal smoke test to verify acceptance of a simple valid change."""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Stable] struct S {};',
+               new='[Stable] struct S { [MinVersion=1] int32 x; };')
+    ])
+
+  def testBasicIncompatibility(self):
+    """Minimal smoke test to verify rejection of a simple invalid change."""
+    self.assertNotBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Stable] struct S {};',
+               new='[Stable] struct S { int32 x; };')
+    ])
+
+  def testIgnoreIfNotStable(self):
+    """We don't care about types not marked [Stable]"""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='struct S {};',
+               new='struct S { int32 x; };')
+    ])
+
+  def testRename(self):
+    """We can do checks for renamed types."""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Stable] struct S {};',
+               new='[Stable, RenamedFrom="S"] struct T {};')
+    ])
+    self.assertNotBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Stable] struct S {};',
+               new='[Stable, RenamedFrom="S"] struct T { int32 x; };')
+    ])
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Stable] struct S {};',
+               new="""\
+               [Stable, RenamedFrom="S"]
+               struct T { [MinVersion=1] int32 x; };
+               """)
+    ])
+
+  def testNewlyStable(self):
+    """We don't care about types newly marked as [Stable]."""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='struct S {};',
+               new='[Stable] struct S { int32 x; };')
+    ])
+
+  def testFileRename(self):
+    """Make sure we can still do compatibility checks after a file rename."""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom', old='[Stable] struct S {};', new=None),
+        Change('bar/bar.mojom',
+               old=None,
+               new='[Stable] struct S { [MinVersion=1] int32 x; };')
+    ])
+    self.assertNotBackwardCompatible([
+        Change('foo/foo.mojom', old='[Stable] struct S {};', new=None),
+        Change('bar/bar.mojom', old=None, new='[Stable] struct S { int32 x; };')
+    ])
+
+  def testWithImport(self):
+    """Ensure that cross-module dependencies do not break the compatibility
+    checking tool."""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old="""\
+               module foo;
+               [Stable] struct S {};
+               """,
+               new="""\
+               module foo;
+               [Stable] struct S { [MinVersion=2] int32 x; };
+               """),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; [MinVersion=1] int32 y; };
+               """)
+    ])
+
+  def testWithMovedDefinition(self):
+    """If a definition moves from one file to another, we should still be able
+    to check compatibility accurately."""
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old="""\
+               module foo;
+               [Stable] struct S {};
+               """,
+               new="""\
+               module foo;
+               """),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable, RenamedFrom="foo.S"] struct S {
+                 [MinVersion=2] int32 x;
+               };
+               [Stable] struct T { S s; [MinVersion=1] int32 y; };
+               """)
+    ])
+
+    self.assertNotBackwardCompatible([
+        Change('foo/foo.mojom',
+               old="""\
+               module foo;
+               [Stable] struct S {};
+               """,
+               new="""\
+               module foo;
+               """),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable, RenamedFrom="foo.S"] struct S { int32 x; };
+               [Stable] struct T { S s; [MinVersion=1] int32 y; };
+               """)
+    ])
+
+  def testWithUnmodifiedImport(self):
+    """Unchanged files in the filesystem are still parsed by the compatibility
+    checking tool if they're imported by a changed file."""
+    self.assertBackwardCompatible([
+        UnchangedFile('foo/foo.mojom', 'module foo; [Stable] struct S {};'),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; [MinVersion=1] int32 x; };
+               """)
+    ])
+
+    self.assertNotBackwardCompatible([
+        UnchangedFile('foo/foo.mojom', 'module foo; [Stable] struct S {};'),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; int32 x; };
+               """)
+    ])
+
+  def testWithPartialImport(self):
+    """The compatibility checking tool correctly parses imports with partial
+    paths."""
+    self.assertBackwardCompatible([
+        UnchangedFile('foo/foo.mojom', 'module foo; [Stable] struct S {};'),
+        Change('foo/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """)
+    ])
+
+    self.assertBackwardCompatible([
+        UnchangedFile('foo/foo.mojom', 'module foo; [Stable] struct S {};'),
+        Change('foo/bar.mojom',
+               old="""\
+               module bar;
+               import "foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """)
+    ])
+
+    self.assertNotBackwardCompatible([
+        UnchangedFile('foo/foo.mojom', 'module foo; [Stable] struct S {};'),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """)
+    ])
+
+    self.assertNotBackwardCompatible([
+        UnchangedFile('foo/foo.mojom', 'module foo; [Stable] struct S {};'),
+        Change('bar/bar.mojom',
+               old="""\
+               module bar;
+               import "foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """,
+               new="""\
+               module bar;
+               import "foo/foo.mojom";
+               [Stable] struct T { foo.S s; };
+               """)
+    ])
+
+  def testNewEnumDefault(self):
+    # Should be backwards compatible since it does not affect the wire format.
+    # This specific case also checks that the backwards compatibility checker
+    # does not throw an error due to the older version of the enum not
+    # specifying [Default].
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Extensible] enum E { One };',
+               new='[Extensible] enum E { [Default] One };')
+    ])
+    self.assertBackwardCompatible([
+        Change('foo/foo.mojom',
+               old='[Extensible] enum E { [Default] One, Two, };',
+               new='[Extensible] enum E { One, [Default] Two, };')
+    ])
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/const_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/const_unittest.py
new file mode 100644
index 00000000..e8ed36a7
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/const_unittest.py
@@ -0,0 +1,90 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from mojom_parser_test_case import MojomParserTestCase
+from mojom.generate import module as mojom
+
+
+class ConstTest(MojomParserTestCase):
+  """Tests constant parsing behavior."""
+
+  def testLiteralInt(self):
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'const int32 k = 42;')
+    self.ParseMojoms([a_mojom])
+    a = self.LoadModule(a_mojom)
+    self.assertEqual(1, len(a.constants))
+    self.assertEqual('k', a.constants[0].mojom_name)
+    self.assertEqual('42', a.constants[0].value)
+
+  def testLiteralFloat(self):
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'const float k = 42.5;')
+    self.ParseMojoms([a_mojom])
+    a = self.LoadModule(a_mojom)
+    self.assertEqual(1, len(a.constants))
+    self.assertEqual('k', a.constants[0].mojom_name)
+    self.assertEqual('42.5', a.constants[0].value)
+
+  def testLiteralString(self):
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'const string k = "woot";')
+    self.ParseMojoms([a_mojom])
+    a = self.LoadModule(a_mojom)
+    self.assertEqual(1, len(a.constants))
+    self.assertEqual('k', a.constants[0].mojom_name)
+    self.assertEqual('"woot"', a.constants[0].value)
+
+  def testEnumConstant(self):
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'module a; enum E { kA = 41, kB };')
+    b_mojom = 'b.mojom'
+    self.WriteFile(
+        b_mojom, """\
+      import "a.mojom";
+      const a.E kE1 = a.E.kB;
+
+      // We also allow value names to be unqualified, implying scope from the
+      // constant's type.
+      const a.E kE2 = kB;
+      """)
+    self.ParseMojoms([a_mojom, b_mojom])
+    a = self.LoadModule(a_mojom)
+    b = self.LoadModule(b_mojom)
+    self.assertEqual(1, len(a.enums))
+    self.assertEqual('E', a.enums[0].mojom_name)
+    self.assertEqual(2, len(b.constants))
+    self.assertEqual('kE1', b.constants[0].mojom_name)
+    self.assertEqual(a.enums[0], b.constants[0].kind)
+    self.assertEqual(a.enums[0].fields[1], b.constants[0].value.field)
+    self.assertEqual(42, b.constants[0].value.field.numeric_value)
+    self.assertEqual('kE2', b.constants[1].mojom_name)
+    self.assertEqual(a.enums[0].fields[1], b.constants[1].value.field)
+    self.assertEqual(42, b.constants[1].value.field.numeric_value)
+
+  def testConstantReference(self):
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'const int32 kA = 42; const int32 kB = kA;')
+    self.ParseMojoms([a_mojom])
+    a = self.LoadModule(a_mojom)
+    self.assertEqual(2, len(a.constants))
+    self.assertEqual('kA', a.constants[0].mojom_name)
+    self.assertEqual('42', a.constants[0].value)
+    self.assertEqual('kB', a.constants[1].mojom_name)
+    self.assertEqual('42', a.constants[1].value)
+
+  def testImportedConstantReference(self):
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'const int32 kA = 42;')
+    b_mojom = 'b.mojom'
+    self.WriteFile(b_mojom, 'import "a.mojom"; const int32 kB = kA;')
+    self.ParseMojoms([a_mojom, b_mojom])
+    a = self.LoadModule(a_mojom)
+    b = self.LoadModule(b_mojom)
+    self.assertEqual(1, len(a.constants))
+    self.assertEqual(1, len(b.constants))
+    self.assertEqual('kA', a.constants[0].mojom_name)
+    self.assertEqual('42', a.constants[0].value)
+    self.assertEqual('kB', b.constants[0].mojom_name)
+    self.assertEqual('42', b.constants[0].value)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/enum_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/enum_unittest.py
new file mode 100644
index 00000000..9269cde5
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/enum_unittest.py
@@ -0,0 +1,120 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class EnumTest(MojomParserTestCase):
+  """Tests enum parsing behavior."""
+
+  def testExplicitValues(self):
+    """Verifies basic parsing of assigned integral values."""
+    types = self.ExtractTypes('enum E { kFoo=0, kBar=2, kBaz };')
+    self.assertEqual('kFoo', types['E'].fields[0].mojom_name)
+    self.assertEqual(0, types['E'].fields[0].numeric_value)
+    self.assertEqual('kBar', types['E'].fields[1].mojom_name)
+    self.assertEqual(2, types['E'].fields[1].numeric_value)
+    self.assertEqual('kBaz', types['E'].fields[2].mojom_name)
+    self.assertEqual(3, types['E'].fields[2].numeric_value)
+
+  def testImplicitValues(self):
+    """Verifies basic automatic assignment of integral values at parse time."""
+    types = self.ExtractTypes('enum E { kFoo, kBar, kBaz };')
+    self.assertEqual('kFoo', types['E'].fields[0].mojom_name)
+    self.assertEqual(0, types['E'].fields[0].numeric_value)
+    self.assertEqual('kBar', types['E'].fields[1].mojom_name)
+    self.assertEqual(1, types['E'].fields[1].numeric_value)
+    self.assertEqual('kBaz', types['E'].fields[2].mojom_name)
+    self.assertEqual(2, types['E'].fields[2].numeric_value)
+
+  def testSameEnumReference(self):
+    """Verifies that an enum value can be assigned from the value of another
+    field within the same enum."""
+    types = self.ExtractTypes('enum E { kA, kB, kFirst=kA };')
+    self.assertEqual('kA', types['E'].fields[0].mojom_name)
+    self.assertEqual(0, types['E'].fields[0].numeric_value)
+    self.assertEqual('kB', types['E'].fields[1].mojom_name)
+    self.assertEqual(1, types['E'].fields[1].numeric_value)
+    self.assertEqual('kFirst', types['E'].fields[2].mojom_name)
+    self.assertEqual(0, types['E'].fields[2].numeric_value)
+
+  def testSameModuleOtherEnumReference(self):
+    """Verifies that an enum value can be assigned from the value of a field
+    in another enum within the same module."""
+    types = self.ExtractTypes('enum E { kA, kB }; enum F { kA = E.kB };')
+    self.assertEqual(1, types['F'].fields[0].numeric_value)
+
+  def testImportedEnumReference(self):
+    """Verifies that an enum value can be assigned from the value of a field
+    in another enum within a different module."""
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'module a; enum E { kFoo=42, kBar };')
+    b_mojom = 'b.mojom'
+    self.WriteFile(b_mojom,
+                   'module b; import "a.mojom"; enum F { kFoo = a.E.kBar };')
+    self.ParseMojoms([a_mojom, b_mojom])
+    b = self.LoadModule(b_mojom)
+
+    self.assertEqual('F', b.enums[0].mojom_name)
+    self.assertEqual('kFoo', b.enums[0].fields[0].mojom_name)
+    self.assertEqual(43, b.enums[0].fields[0].numeric_value)
+
+  def testConstantReference(self):
+    """Verifies that an enum value can be assigned from the value of an
+    integral constant within the same module."""
+    types = self.ExtractTypes('const int32 kFoo = 42; enum E { kA = kFoo };')
+    self.assertEqual(42, types['E'].fields[0].numeric_value)
+
+  def testInvalidConstantReference(self):
+    """Verifies that enum values cannot be assigned from the value of
+    non-integral constants."""
+    with self.assertRaisesRegexp(ValueError, 'not an integer'):
+      self.ExtractTypes('const float kFoo = 1.0; enum E { kA = kFoo };')
+    with self.assertRaisesRegexp(ValueError, 'not an integer'):
+      self.ExtractTypes('const double kFoo = 1.0; enum E { kA = kFoo };')
+    with self.assertRaisesRegexp(ValueError, 'not an integer'):
+      self.ExtractTypes('const string kFoo = "lol"; enum E { kA = kFoo };')
+
+  def testImportedConstantReference(self):
+    """Verifies that an enum value can be assigned from the value of an integral
+    constant within an imported module."""
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'module a; const int32 kFoo = 37;')
+    b_mojom = 'b.mojom'
+    self.WriteFile(b_mojom,
+                   'module b; import "a.mojom"; enum F { kFoo = a.kFoo };')
+    self.ParseMojoms([a_mojom, b_mojom])
+    b = self.LoadModule(b_mojom)
+
+    self.assertEqual('F', b.enums[0].mojom_name)
+    self.assertEqual('kFoo', b.enums[0].fields[0].mojom_name)
+    self.assertEqual(37, b.enums[0].fields[0].numeric_value)
+
+  def testEnumAttributesAreEnums(self):
+    """Verifies that enum values in attributes are really enum types."""
+    a_mojom = 'a.mojom'
+    self.WriteFile(a_mojom, 'module a; enum E { kFoo, kBar };')
+    b_mojom = 'b.mojom'
+    self.WriteFile(
+        b_mojom, 'module b;'
+        'import "a.mojom";'
+        '[MooCow=a.E.kFoo]'
+        'interface Foo { Foo(); };')
+    self.ParseMojoms([a_mojom, b_mojom])
+    b = self.LoadModule(b_mojom)
+    self.assertEqual(b.interfaces[0].attributes['MooCow'].mojom_name, 'kFoo')
+
+  def testConstantAttributes(self):
+    """Verifies that constants as attributes are translated to the constant."""
+    a_mojom = 'a.mojom'
+    self.WriteFile(
+        a_mojom, 'module a;'
+        'enum E { kFoo, kBar };'
+        'const E kB = E.kFoo;'
+        '[Attr=kB] interface Hello { Foo(); };')
+    self.ParseMojoms([a_mojom])
+    a = self.LoadModule(a_mojom)
+    self.assertEqual(a.interfaces[0].attributes['Attr'].mojom_name, 'kB')
+    self.assertEquals(a.interfaces[0].attributes['Attr'].value.mojom_name,
+                      'kFoo')
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/feature_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/feature_unittest.py
new file mode 100644
index 00000000..5f014e1c
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/feature_unittest.py
@@ -0,0 +1,84 @@
+# Copyright 2023 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class FeatureTest(MojomParserTestCase):
+  """Tests feature parsing behavior."""
+  def testFeatureOff(self):
+    """Verifies basic parsing of feature types."""
+    types = self.ExtractTypes("""
+      // e.g. BASE_DECLARE_FEATURE(kFeature);
+      [AttributeOne=ValueOne]
+      feature kFeature {
+        // BASE_FEATURE(kFeature,"MyFeature",
+        //     base::FEATURE_DISABLED_BY_DEFAULT);
+        const string name = "MyFeature";
+        const bool default_state = false;
+      };
+    """)
+    self.assertEqual('name', types['kFeature'].constants[0].mojom_name)
+    self.assertEqual('"MyFeature"', types['kFeature'].constants[0].value)
+    self.assertEqual('default_state', types['kFeature'].constants[1].mojom_name)
+    self.assertEqual('false', types['kFeature'].constants[1].value)
+
+  def testFeatureOn(self):
+    """Verifies basic parsing of feature types."""
+    types = self.ExtractTypes("""
+      // e.g. BASE_DECLARE_FEATURE(kFeature);
+      feature kFeature {
+        // BASE_FEATURE(kFeature,"MyFeature",
+        //     base::FEATURE_ENABLED_BY_DEFAULT);
+        const string name = "MyFeature";
+        const bool default_state = true;
+      };
+    """)
+    self.assertEqual('name', types['kFeature'].constants[0].mojom_name)
+    self.assertEqual('"MyFeature"', types['kFeature'].constants[0].value)
+    self.assertEqual('default_state', types['kFeature'].constants[1].mojom_name)
+    self.assertEqual('true', types['kFeature'].constants[1].value)
+
+  def testFeatureWeakKeyword(self):
+    """Verifies that `feature` is a weak keyword."""
+    types = self.ExtractTypes("""
+      // e.g. BASE_DECLARE_FEATURE(kFeature);
+      [AttributeOne=ValueOne]
+      feature kFeature {
+        // BASE_FEATURE(kFeature,"MyFeature",
+        //     base::FEATURE_DISABLED_BY_DEFAULT);
+        const string name = "MyFeature";
+        const bool default_state = false;
+      };
+      struct MyStruct {
+         bool feature = true;
+      };
+      interface InterfaceName {
+         Method(string feature) => (int32 feature);
+      };
+    """)
+    self.assertEqual('name', types['kFeature'].constants[0].mojom_name)
+    self.assertEqual('"MyFeature"', types['kFeature'].constants[0].value)
+    self.assertEqual('default_state', types['kFeature'].constants[1].mojom_name)
+    self.assertEqual('false', types['kFeature'].constants[1].value)
+
+  def testFeatureAttributesAreFeatures(self):
+    """Verifies that feature values in attributes are really feature types."""
+    a_mojom = 'a.mojom'
+    self.WriteFile(
+        a_mojom, 'module a;'
+        'feature F { const string name = "f";'
+        'const bool default_state = false; };')
+    b_mojom = 'b.mojom'
+    self.WriteFile(
+        b_mojom, 'module b;'
+        'import "a.mojom";'
+        'feature G'
+        '{const string name = "g"; const bool default_state = false;};'
+        '[Attri=a.F] interface Foo { Foo(); };'
+        '[Boink=G] interface Bar {};')
+    self.ParseMojoms([a_mojom, b_mojom])
+    b = self.LoadModule(b_mojom)
+    self.assertEqual(b.interfaces[0].attributes['Attri'].mojom_name, 'F')
+    self.assertEqual(b.interfaces[1].attributes['Boink'].mojom_name, 'G')
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/BUILD.gn b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/BUILD.gn
new file mode 100644
index 00000000..a0edf0eb
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/BUILD.gn
@@ -0,0 +1,43 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+group("mojom") {
+  data = [
+    "__init__.py",
+    "error.py",
+    "fileutil.py",
+    "generate/__init__.py",
+    "generate/check.py",
+    "generate/generator.py",
+    "generate/module.py",
+    "generate/pack.py",
+    "generate/template_expander.py",
+    "generate/translate.py",
+    "parse/__init__.py",
+    "parse/ast.py",
+    "parse/conditional_features.py",
+    "parse/lexer.py",
+    "parse/parser.py",
+
+    # Third-party module dependencies
+    "//third_party/jinja2/",
+    "//third_party/ply/",
+  ]
+}
+
+group("tests") {
+  data = [
+    "fileutil_unittest.py",
+    "generate/generator_unittest.py",
+    "generate/module_unittest.py",
+    "generate/pack_unittest.py",
+    "generate/translate_unittest.py",
+    "parse/ast_unittest.py",
+    "parse/conditional_features_unittest.py",
+    "parse/lexer_unittest.py",
+    "parse/parser_unittest.py",
+  ]
+
+  public_deps = [ ":mojom" ]
+}
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/__init__.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/__init__.py
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/error.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/error.py
new file mode 100644
index 00000000..dd53b835
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/error.py
@@ -0,0 +1,28 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+
+class Error(Exception):
+  """Base class for Mojo IDL bindings parser/generator errors."""
+
+  def __init__(self, filename, message, lineno=None, addenda=None, **kwargs):
+    """|filename| is the (primary) file which caused the error, |message| is the
+    error message, |lineno| is the 1-based line number (or |None| if not
+    applicable/available), and |addenda| is a list of additional lines to append
+    to the final error message."""
+    Exception.__init__(self, **kwargs)
+    self.filename = filename
+    self.message = message
+    self.lineno = lineno
+    self.addenda = addenda
+
+  def __str__(self):
+    if self.lineno:
+      s = "%s:%d: Error: %s" % (self.filename, self.lineno, self.message)
+    else:
+      s = "%s: Error: %s" % (self.filename, self.message)
+    return "\n".join([s] + self.addenda) if self.addenda else s
+
+  def __repr__(self):
+    return str(self)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/fileutil.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/fileutil.py
new file mode 100644
index 00000000..124f12c1
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/fileutil.py
@@ -0,0 +1,44 @@
+# Copyright 2015 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import errno
+import os.path
+import sys
+
+
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, tail = os.path.split(path)
+    if not tail:
+      return None
+    if tail == dirname:
+      return path
+
+
+def EnsureDirectoryExists(path, always_try_to_create=False):
+  """A wrapper for os.makedirs that does not error if the directory already
+  exists. A different process could be racing to create this directory."""
+
+  if not os.path.exists(path) or always_try_to_create:
+    try:
+      os.makedirs(path)
+    except OSError as e:
+      # There may have been a race to create this directory.
+      if e.errno != errno.EEXIST:
+        raise
+
+
+def AddLocalRepoThirdPartyDirToModulePath():
+  """Helper function to find the top-level directory of this script's repository
+  assuming the script falls somewhere within a 'mojo' directory, and insert the
+  top-level 'third_party' directory early in the module search path. Used to
+  ensure that third-party dependencies provided within the repository itself
+  (e.g. Chromium sources include snapshots of jinja2 and ply) are preferred over
+  locally installed system library packages."""
+  toplevel_dir = _GetDirAbove('mojo')
+  if toplevel_dir:
+    sys.path.insert(1, os.path.join(toplevel_dir, 'third_party'))
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/fileutil_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/fileutil_unittest.py
new file mode 100644
index 00000000..c93d2289
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/fileutil_unittest.py
@@ -0,0 +1,37 @@
+# Copyright 2015 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os.path
+import shutil
+import tempfile
+import unittest
+
+from mojom import fileutil
+
+class FileUtilTest(unittest.TestCase):
+  def testEnsureDirectoryExists(self):
+    """Test that EnsureDirectoryExists functions correctly."""
+
+    temp_dir = tempfile.mkdtemp()
+    try:
+      self.assertTrue(os.path.exists(temp_dir))
+
+      # Directory does not exist, yet.
+      full = os.path.join(temp_dir, "foo", "bar")
+      self.assertFalse(os.path.exists(full))
+
+      # Create the directory.
+      fileutil.EnsureDirectoryExists(full)
+      self.assertTrue(os.path.exists(full))
+
+      # Trying to create it again does not cause an error.
+      fileutil.EnsureDirectoryExists(full)
+      self.assertTrue(os.path.exists(full))
+
+      # Bypass check for directory existence to tickle error handling that
+      # occurs in response to a race.
+      fileutil.EnsureDirectoryExists(full, always_try_to_create=True)
+      self.assertTrue(os.path.exists(full))
+    finally:
+      shutil.rmtree(temp_dir)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/__init__.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/__init__.py
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/check.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/check.py
new file mode 100644
index 00000000..1efe2022
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/check.py
@@ -0,0 +1,26 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Code shared by the various pre-generation mojom checkers."""
+
+
+class CheckException(Exception):
+  def __init__(self, module, message):
+    self.module = module
+    self.message = message
+    super().__init__(self.message)
+
+  def __str__(self):
+    return "Failed mojo pre-generation check for {}:\n{}".format(
+        self.module.path, self.message)
+
+
+class Check:
+  def __init__(self, module):
+    self.module = module
+
+  def CheckModule(self):
+    """ Subclass should return True if its Checks pass, and throw an
+    exception otherwise. CheckModule will be called immediately before
+    mojom.generate.Generator.GenerateFiles()"""
+    raise NotImplementedError("Subclasses must override/implement this method")
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/generator.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/generator.py
new file mode 100644
index 00000000..96fe3a2d
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/generator.py
@@ -0,0 +1,328 @@
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Code shared by the various language-specific code generators."""
+
+from __future__ import print_function
+
+from functools import partial
+import os.path
+import re
+
+from mojom import fileutil
+from mojom.generate import module as mojom
+from mojom.generate import pack
+
+
+def ExpectedArraySize(kind):
+  if mojom.IsArrayKind(kind):
+    return kind.length
+  return None
+
+
+def SplitCamelCase(identifier):
+  """Splits a camel-cased |identifier| and returns a list of lower-cased
+  strings.
+  """
+  # Add underscores after uppercase letters when appropriate. An uppercase
+  # letter is considered the end of a word if it is followed by an upper and a
+  # lower. E.g. URLLoaderFactory -> URL_LoaderFactory
+  identifier = re.sub('([A-Z][0-9]*)(?=[A-Z][0-9]*[a-z])', r'\1_', identifier)
+  # Add underscores after lowercase letters when appropriate. A lowercase letter
+  # is considered the end of a word if it is followed by an upper.
+  # E.g. URLLoaderFactory -> URLLoader_Factory
+  identifier = re.sub('([a-z][0-9]*)(?=[A-Z])', r'\1_', identifier)
+  return [x.lower() for x in identifier.split('_')]
+
+
+def ToCamel(identifier, lower_initial=False, digits_split=False, delimiter='_'):
+  """Splits |identifier| using |delimiter|, makes the first character of each
+  word uppercased (but makes the first character of the first word lowercased
+  if |lower_initial| is set to True), and joins the words. Please note that for
+  each word, all the characters except the first one are untouched.
+  """
+  result = ''
+  capitalize_next = True
+  for i in range(len(identifier)):
+    if identifier[i] == delimiter:
+      capitalize_next = True
+    elif digits_split and identifier[i].isdigit():
+      capitalize_next = True
+      result += identifier[i]
+    elif capitalize_next:
+      capitalize_next = False
+      result += identifier[i].upper()
+    else:
+      result += identifier[i]
+
+  if lower_initial and result:
+    result = result[0].lower() + result[1:]
+
+  return result
+
+
+def _ToSnakeCase(identifier, upper=False):
+  """Splits camel-cased |identifier| into lower case words, removes the first
+  word if it's "k" and joins them using "_" e.g. for "URLLoaderFactory", returns
+  "URL_LOADER_FACTORY" if upper, otherwise "url_loader_factory".
+  """
+  words = SplitCamelCase(identifier)
+  if words[0] == 'k' and len(words) > 1:
+    words = words[1:]
+
+  # Variables cannot start with a digit
+  if (words[0][0].isdigit()):
+    words[0] = '_' + words[0]
+
+
+  if upper:
+    words = map(lambda x: x.upper(), words)
+
+  return '_'.join(words)
+
+
+def ToUpperSnakeCase(identifier):
+  """Splits camel-cased |identifier| into lower case words, removes the first
+  word if it's "k" and joins them using "_" e.g. for "URLLoaderFactory", returns
+  "URL_LOADER_FACTORY".
+  """
+  return _ToSnakeCase(identifier, upper=True)
+
+
+def ToLowerSnakeCase(identifier):
+  """Splits camel-cased |identifier| into lower case words, removes the first
+  word if it's "k" and joins them using "_" e.g. for "URLLoaderFactory", returns
+  "url_loader_factory".
+  """
+  return _ToSnakeCase(identifier, upper=False)
+
+
+class Stylizer:
+  """Stylizers specify naming rules to map mojom names to names in generated
+  code. For example, if you would like method_name in mojom to be mapped to
+  MethodName in the generated code, you need to define a subclass of Stylizer
+  and override StylizeMethod to do the conversion."""
+
+  def StylizeConstant(self, mojom_name):
+    return mojom_name
+
+  def StylizeField(self, mojom_name):
+    return mojom_name
+
+  def StylizeStruct(self, mojom_name):
+    return mojom_name
+
+  def StylizeUnion(self, mojom_name):
+    return mojom_name
+
+  def StylizeParameter(self, mojom_name):
+    return mojom_name
+
+  def StylizeMethod(self, mojom_name):
+    return mojom_name
+
+  def StylizeInterface(self, mojom_name):
+    return mojom_name
+
+  def StylizeEnumField(self, mojom_name):
+    return mojom_name
+
+  def StylizeEnum(self, mojom_name):
+    return mojom_name
+
+  def StylizeFeature(self, mojom_name):
+    return mojom_name
+
+  def StylizeModule(self, mojom_namespace):
+    return mojom_namespace
+
+
+def WriteFile(contents, full_path):
+  # If |contents| is same with the file content, we skip updating.
+  if not isinstance(contents, bytes):
+    data = contents.encode('utf8')
+  else:
+    data = contents
+
+  if os.path.isfile(full_path):
+    with open(full_path, 'rb') as destination_file:
+      if destination_file.read() == data:
+        return
+
+  # Make sure the containing directory exists.
+  full_dir = os.path.dirname(full_path)
+  fileutil.EnsureDirectoryExists(full_dir)
+
+  # Dump the data to disk.
+  with open(full_path, 'wb') as f:
+    f.write(data)
+
+
+def AddComputedData(module):
+  """Adds computed data to the given module. The data is computed once and
+  used repeatedly in the generation process."""
+
+  def _AddStructComputedData(exported, struct):
+    struct.packed = pack.PackedStruct(struct)
+    struct.bytes = pack.GetByteLayout(struct.packed)
+    struct.versions = pack.GetVersionInfo(struct.packed)
+    struct.exported = exported
+
+  def _AddInterfaceComputedData(interface):
+    interface.version = 0
+    for method in interface.methods:
+      # this field is never scrambled
+      method.sequential_ordinal = method.ordinal
+
+      if method.min_version is not None:
+        interface.version = max(interface.version, method.min_version)
+
+      method.param_struct = _GetStructFromMethod(method)
+      if interface.stable:
+        method.param_struct.attributes[mojom.ATTRIBUTE_STABLE] = True
+        if method.explicit_ordinal is None:
+          raise Exception(
+              'Stable interfaces must declare explicit method ordinals. The '
+              'method %s on stable interface %s does not declare an explicit '
+              'ordinal.' % (method.mojom_name, interface.qualified_name))
+      interface.version = max(interface.version,
+                              method.param_struct.versions[-1].version)
+
+      if method.response_parameters is not None:
+        method.response_param_struct = _GetResponseStructFromMethod(method)
+        if interface.stable:
+          method.response_param_struct.attributes[mojom.ATTRIBUTE_STABLE] = True
+        interface.version = max(
+            interface.version,
+            method.response_param_struct.versions[-1].version)
+      else:
+        method.response_param_struct = None
+
+  def _GetStructFromMethod(method):
+    """Converts a method's parameters into the fields of a struct."""
+    params_class = "%s_%s_Params" % (method.interface.mojom_name,
+                                     method.mojom_name)
+    struct = mojom.Struct(params_class,
+                          module=method.interface.module,
+                          attributes={})
+    for param in method.parameters:
+      struct.AddField(
+          param.mojom_name,
+          param.kind,
+          param.ordinal,
+          attributes=param.attributes)
+    _AddStructComputedData(False, struct)
+    return struct
+
+  def _GetResponseStructFromMethod(method):
+    """Converts a method's response_parameters into the fields of a struct."""
+    params_class = "%s_%s_ResponseParams" % (method.interface.mojom_name,
+                                             method.mojom_name)
+    struct = mojom.Struct(params_class,
+                          module=method.interface.module,
+                          attributes={})
+    for param in method.response_parameters:
+      struct.AddField(
+          param.mojom_name,
+          param.kind,
+          param.ordinal,
+          attributes=param.attributes)
+    _AddStructComputedData(False, struct)
+    return struct
+
+  for struct in module.structs:
+    _AddStructComputedData(True, struct)
+  for interface in module.interfaces:
+    _AddInterfaceComputedData(interface)
+
+
+class Generator:
+  # Pass |output_dir| to emit files to disk. Omit |output_dir| to echo all
+  # files to stdout.
+  def __init__(self,
+               module,
+               output_dir=None,
+               typemap=None,
+               variant=None,
+               bytecode_path=None,
+               for_blink=False,
+               js_generate_struct_deserializers=False,
+               export_attribute=None,
+               export_header=None,
+               generate_non_variant_code=False,
+               support_lazy_serialization=False,
+               disallow_native_types=False,
+               disallow_interfaces=False,
+               generate_message_ids=False,
+               generate_fuzzing=False,
+               enable_kythe_annotations=False,
+               extra_cpp_template_paths=None,
+               generate_extra_cpp_only=False):
+    self.module = module
+    self.output_dir = output_dir
+    self.typemap = typemap or {}
+    self.variant = variant
+    self.bytecode_path = bytecode_path
+    self.for_blink = for_blink
+    self.js_generate_struct_deserializers = js_generate_struct_deserializers
+    self.export_attribute = export_attribute
+    self.export_header = export_header
+    self.generate_non_variant_code = generate_non_variant_code
+    self.support_lazy_serialization = support_lazy_serialization
+    self.disallow_native_types = disallow_native_types
+    self.disallow_interfaces = disallow_interfaces
+    self.generate_message_ids = generate_message_ids
+    self.generate_fuzzing = generate_fuzzing
+    self.enable_kythe_annotations = enable_kythe_annotations
+    self.extra_cpp_template_paths = extra_cpp_template_paths
+    self.generate_extra_cpp_only = generate_extra_cpp_only
+
+  def Write(self, contents, filename):
+    if self.output_dir is None:
+      print(contents)
+      return
+    full_path = os.path.join(self.output_dir, filename)
+    WriteFile(contents, full_path)
+
+  def OptimizeEmpty(self, contents):
+    # Look for .cc files that contain no actual code. There are many of these
+    # and they collectively take a while to compile.
+    lines = contents.splitlines()
+
+    for line in lines:
+      if line.startswith('#') or line.startswith('//'):
+        continue
+      if re.match(r'namespace .* {', line) or re.match(r'}.*//.*namespace',
+                                                       line):
+        continue
+      if line.strip():
+        # There is some actual code - return the unmodified contents.
+        return contents
+
+    # If we reach here then we have a .cc file with no actual code. The
+    # includes are therefore unneeded and can be removed.
+    new_lines = [line for line in lines if not line.startswith('#include')]
+    if len(new_lines) < len(lines):
+      new_lines.append('')
+      new_lines.append('// Includes removed due to no code being generated.')
+    return '\n'.join(new_lines)
+
+  def WriteWithComment(self, contents, filename):
+    generator_name = "mojom_bindings_generator.py"
+    comment = r"// %s is auto generated by %s, do not edit" % (filename,
+                                                               generator_name)
+    contents = comment + '\n' + '\n' + contents;
+    if filename.endswith('.cc'):
+      contents = self.OptimizeEmpty(contents)
+    self.Write(contents, filename)
+
+  def GenerateFiles(self, args):
+    raise NotImplementedError("Subclasses must override/implement this method")
+
+  def GetJinjaParameters(self):
+    """Returns default constructor parameters for the jinja environment."""
+    return {}
+
+  def GetGlobals(self):
+    """Returns global mappings for the template generation."""
+    return {}
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/generator_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/generator_unittest.py
new file mode 100644
index 00000000..7143e07c
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/generator_unittest.py
@@ -0,0 +1,71 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import importlib.util
+import os.path
+import sys
+import unittest
+
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, tail = os.path.split(path)
+    assert tail
+    if tail == dirname:
+      return path
+
+
+try:
+  importlib.util.find_spec("mojom")
+except ImportError:
+  sys.path.append(os.path.join(_GetDirAbove("pylib"), "pylib"))
+from mojom.generate import generator
+
+class StringManipulationTest(unittest.TestCase):
+  """generator contains some string utilities, this tests only those."""
+
+  def testSplitCamelCase(self):
+    self.assertEquals(["camel", "case"], generator.SplitCamelCase("CamelCase"))
+    self.assertEquals(["url", "loader", "factory"],
+                      generator.SplitCamelCase('URLLoaderFactory'))
+    self.assertEquals(["get99", "entries"],
+                      generator.SplitCamelCase('Get99Entries'))
+    self.assertEquals(["get99entries"],
+                      generator.SplitCamelCase('Get99entries'))
+
+  def testToCamel(self):
+    self.assertEquals("CamelCase", generator.ToCamel("camel_case"))
+    self.assertEquals("CAMELCASE", generator.ToCamel("CAMEL_CASE"))
+    self.assertEquals("camelCase",
+                      generator.ToCamel("camel_case", lower_initial=True))
+    self.assertEquals("CamelCase", generator.ToCamel(
+        "camel case", delimiter=' '))
+    self.assertEquals("CaMelCaSe", generator.ToCamel("caMel_caSe"))
+    self.assertEquals("L2Tp", generator.ToCamel("l2tp", digits_split=True))
+    self.assertEquals("l2tp", generator.ToCamel("l2tp", lower_initial=True))
+
+  def testToSnakeCase(self):
+    self.assertEquals("snake_case", generator.ToLowerSnakeCase("SnakeCase"))
+    self.assertEquals("snake_case", generator.ToLowerSnakeCase("snakeCase"))
+    self.assertEquals("snake_case", generator.ToLowerSnakeCase("SnakeCASE"))
+    self.assertEquals("snake_d3d11_case",
+                      generator.ToLowerSnakeCase("SnakeD3D11Case"))
+    self.assertEquals("snake_d3d11_case",
+                      generator.ToLowerSnakeCase("SnakeD3d11Case"))
+    self.assertEquals("snake_d3d11_case",
+                      generator.ToLowerSnakeCase("snakeD3d11Case"))
+    self.assertEquals("SNAKE_CASE", generator.ToUpperSnakeCase("SnakeCase"))
+    self.assertEquals("SNAKE_CASE", generator.ToUpperSnakeCase("snakeCase"))
+    self.assertEquals("SNAKE_CASE", generator.ToUpperSnakeCase("SnakeCASE"))
+    self.assertEquals("SNAKE_D3D11_CASE",
+                      generator.ToUpperSnakeCase("SnakeD3D11Case"))
+    self.assertEquals("SNAKE_D3D11_CASE",
+                      generator.ToUpperSnakeCase("SnakeD3d11Case"))
+    self.assertEquals("SNAKE_D3D11_CASE",
+                      generator.ToUpperSnakeCase("snakeD3d11Case"))
+
+if __name__ == "__main__":
+  unittest.main()
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/module.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/module.py
new file mode 100644
index 00000000..ca71059d
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/module.py
@@ -0,0 +1,2059 @@
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This module's classes provide an interface to mojo modules. Modules are
+# collections of interfaces and structs to be used by mojo ipc clients and
+# servers.
+#
+# A simple interface would be created this way:
+# module = mojom.generate.module.Module('Foo')
+# interface = module.AddInterface('Bar')
+# method = interface.AddMethod('Tat', 0)
+# method.AddParameter('baz', 0, mojom.INT32)
+
+import pickle
+from collections import OrderedDict
+from uuid import UUID
+
+# pylint: disable=raise-missing-from
+
+
+class BackwardCompatibilityChecker:
+  """Used for memoization while recursively checking two type definitions for
+  backward-compatibility."""
+
+  def __init__(self):
+    self._cache = {}
+
+  def IsBackwardCompatible(self, new_kind, old_kind):
+    key = (new_kind, old_kind)
+    result = self._cache.get(key)
+    if result is None:
+      # Assume they're compatible at first to effectively ignore recursive
+      # checks between these types, e.g. if both kinds are a struct or union
+      # that references itself in a field.
+      self._cache[key] = True
+      result = new_kind.IsBackwardCompatible(old_kind, self)
+      self._cache[key] = result
+    return result
+
+
+# We use our own version of __repr__ when displaying the AST, as the
+# AST currently doesn't capture which nodes are reference (e.g. to
+# types) and which nodes are definitions. This allows us to e.g. print
+# the definition of a struct when it's defined inside a module, but
+# only print its name when it's referenced in e.g. a method parameter.
+def Repr(obj, as_ref=True):
+  """A version of __repr__ that can distinguish references.
+
+  Sometimes we like to print an object's full representation
+  (e.g. with its fields) and sometimes we just want to reference an
+  object that was printed in full elsewhere. This function allows us
+  to make that distinction.
+
+  Args:
+    obj: The object whose string representation we compute.
+    as_ref: If True, use the short reference representation.
+
+  Returns:
+    A str representation of |obj|.
+  """
+  if hasattr(obj, 'Repr'):
+    return obj.Repr(as_ref=as_ref)
+  # Since we cannot implement Repr for existing container types, we
+  # handle them here.
+  if isinstance(obj, list):
+    if not obj:
+      return '[]'
+    return ('[\n%s\n]' %
+            (',\n'.join('    %s' % Repr(elem, as_ref).replace('\n', '\n    ')
+                        for elem in obj)))
+  if isinstance(obj, dict):
+    if not obj:
+      return '{}'
+    return ('{\n%s\n}' % (',\n'.join('    %s: %s' %
+                                     (Repr(key, as_ref).replace('\n', '\n    '),
+                                      Repr(val, as_ref).replace('\n', '\n    '))
+                                     for key, val in obj.items())))
+  return repr(obj)
+
+
+def GenericRepr(obj, names):
+  """Compute generic Repr for |obj| based on the attributes in |names|.
+
+  Args:
+    obj: The object to compute a Repr for.
+    names: A dict from attribute names to include, to booleans
+        specifying whether those attributes should be shown as
+        references or not.
+
+  Returns:
+    A str representation of |obj|.
+  """
+
+  def ReprIndent(name, as_ref):
+    return '    %s=%s' % (name, Repr(getattr(obj, name), as_ref).replace(
+        '\n', '\n    '))
+
+  return '%s(\n%s\n)' % (obj.__class__.__name__, ',\n'.join(
+      ReprIndent(name, as_ref) for (name, as_ref) in names.items()))
+
+
+class Kind:
+  """Kind represents a type (e.g. int8, string).
+
+  Attributes:
+    spec: A string uniquely identifying the type. May be None.
+    module: {Module} The defining module. Set to None for built-in types.
+    parent_kind: The enclosing type. For example, an enum defined
+        inside an interface has that interface as its parent. May be None.
+    is_nullable: True if the type is nullable.
+  """
+
+  def __init__(self, spec=None, is_nullable=False, module=None):
+    self.spec = spec
+    self.module = module
+    self.parent_kind = None
+    self.is_nullable = is_nullable
+    self.shared_definition = {}
+
+  @classmethod
+  def AddSharedProperty(cls, name):
+    """Adds a property |name| to |cls|, which accesses the corresponding item in
+       |shared_definition|.
+
+       The reason of adding such indirection is to enable sharing definition
+       between a reference kind and its nullable variation. For example:
+         a = Struct('test_struct_1')
+         b = a.MakeNullableKind()
+         a.name = 'test_struct_2'
+         print(b.name)  # Outputs 'test_struct_2'.
+    """
+    def Get(self):
+      try:
+        return self.shared_definition[name]
+      except KeyError:  # Must raise AttributeError if property doesn't exist.
+        raise AttributeError
+
+    def Set(self, value):
+      self.shared_definition[name] = value
+
+    setattr(cls, name, property(Get, Set))
+
+  def Repr(self, as_ref=True):
+    # pylint: disable=unused-argument
+    return '<%s spec=%r is_nullable=%r>' % (self.__class__.__name__, self.spec,
+                                            self.is_nullable)
+
+  def __repr__(self):
+    # Gives us a decent __repr__ for all kinds.
+    return self.Repr()
+
+  def __eq__(self, rhs):
+    # pylint: disable=unidiomatic-typecheck
+    return (type(self) == type(rhs)
+            and (self.spec, self.parent_kind, self.is_nullable)
+            == (rhs.spec, rhs.parent_kind, rhs.is_nullable))
+
+  def __hash__(self):
+    # TODO(crbug.com/1060471): Remove this and other __hash__ methods on Kind
+    # and its subclasses. This is to support existing generator code which uses
+    # some primitive Kinds as dict keys. The default hash (object identity)
+    # breaks these dicts when a pickled Module instance is unpickled and used
+    # during a subsequent run of the parser.
+    return hash((self.spec, self.parent_kind, self.is_nullable))
+
+  # pylint: disable=unused-argument
+  def IsBackwardCompatible(self, rhs, checker):
+    return self == rhs
+
+
+class ValueKind(Kind):
+  """ValueKind represents values that aren't reference kinds.
+
+  The primary difference is the wire representation for nullable value kinds
+  still reserves space for the value type itself, even if that value itself
+  is logically null.
+  """
+  def __init__(self, spec=None, is_nullable=False, module=None):
+    assert spec is None or is_nullable == spec.startswith('?')
+    Kind.__init__(self, spec, is_nullable, module)
+
+  def MakeNullableKind(self):
+    assert not self.is_nullable
+
+    if self == BOOL:
+      return NULLABLE_BOOL
+    if self == INT8:
+      return NULLABLE_INT8
+    if self == INT16:
+      return NULLABLE_INT16
+    if self == INT32:
+      return NULLABLE_INT32
+    if self == INT64:
+      return NULLABLE_INT64
+    if self == UINT8:
+      return NULLABLE_UINT8
+    if self == UINT16:
+      return NULLABLE_UINT16
+    if self == UINT32:
+      return NULLABLE_UINT32
+    if self == UINT64:
+      return NULLABLE_UINT64
+    if self == FLOAT:
+      return NULLABLE_FLOAT
+    if self == DOUBLE:
+      return NULLABLE_DOUBLE
+
+    nullable_kind = type(self)()
+    nullable_kind.shared_definition = self.shared_definition
+    if self.spec is not None:
+      nullable_kind.spec = '?' + self.spec
+    nullable_kind.is_nullable = True
+    nullable_kind.parent_kind = self.parent_kind
+    nullable_kind.module = self.module
+
+    return nullable_kind
+
+  def MakeUnnullableKind(self):
+    assert self.is_nullable
+
+    if self == NULLABLE_BOOL:
+      return BOOL
+    if self == NULLABLE_INT8:
+      return INT8
+    if self == NULLABLE_INT16:
+      return INT16
+    if self == NULLABLE_INT32:
+      return INT32
+    if self == NULLABLE_INT64:
+      return INT64
+    if self == NULLABLE_UINT8:
+      return UINT8
+    if self == NULLABLE_UINT16:
+      return UINT16
+    if self == NULLABLE_UINT32:
+      return UINT32
+    if self == NULLABLE_UINT64:
+      return UINT64
+    if self == NULLABLE_FLOAT:
+      return FLOAT
+    if self == NULLABLE_DOUBLE:
+      return DOUBLE
+
+    nullable_kind = type(self)()
+    nullable_kind.shared_definition = self.shared_definition
+    if self.spec is not None:
+      nullable_kind.spec = self.spec[1:]
+    nullable_kind.is_nullable = False
+    nullable_kind.parent_kind = self.parent_kind
+    nullable_kind.module = self.module
+
+    return nullable_kind
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, ValueKind) and super().__eq__(rhs))
+
+  def __hash__(self):  # pylint: disable=useless-super-delegation
+    return super().__hash__()
+
+
+class ReferenceKind(Kind):
+  """ReferenceKind represents pointer and handle types.
+
+  A type is nullable if null (for pointer types) or invalid handle (for handle
+  types) is a legal value for the type.
+  """
+
+  def __init__(self, spec=None, is_nullable=False, module=None):
+    assert spec is None or is_nullable == spec.startswith('?')
+    Kind.__init__(self, spec, is_nullable, module)
+
+  def MakeNullableKind(self):
+    assert not self.is_nullable
+
+    if self == STRING:
+      return NULLABLE_STRING
+    if self == HANDLE:
+      return NULLABLE_HANDLE
+    if self == DCPIPE:
+      return NULLABLE_DCPIPE
+    if self == DPPIPE:
+      return NULLABLE_DPPIPE
+    if self == MSGPIPE:
+      return NULLABLE_MSGPIPE
+    if self == SHAREDBUFFER:
+      return NULLABLE_SHAREDBUFFER
+    if self == PLATFORMHANDLE:
+      return NULLABLE_PLATFORMHANDLE
+
+    nullable_kind = type(self)()
+    nullable_kind.shared_definition = self.shared_definition
+    if self.spec is not None:
+      nullable_kind.spec = '?' + self.spec
+    nullable_kind.is_nullable = True
+    nullable_kind.parent_kind = self.parent_kind
+    nullable_kind.module = self.module
+
+    return nullable_kind
+
+  def MakeUnnullableKind(self):
+    assert self.is_nullable
+
+    if self == NULLABLE_STRING:
+      return STRING
+    if self == NULLABLE_HANDLE:
+      return HANDLE
+    if self == NULLABLE_DCPIPE:
+      return DCPIPE
+    if self == NULLABLE_DPPIPE:
+      return DPPIPE
+    if self == NULLABLE_MSGPIPE:
+      return MSGPIPE
+    if self == NULLABLE_SHAREDBUFFER:
+      return SHAREDBUFFER
+    if self == NULLABLE_PLATFORMHANDLE:
+      return PLATFORMHANDLE
+
+    unnullable_kind = type(self)()
+    unnullable_kind.shared_definition = self.shared_definition
+    if self.spec is not None:
+      assert self.spec[0] == '?'
+      unnullable_kind.spec = self.spec[1:]
+    unnullable_kind.is_nullable = False
+    unnullable_kind.parent_kind = self.parent_kind
+    unnullable_kind.module = self.module
+
+    return unnullable_kind
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, ReferenceKind) and super().__eq__(rhs))
+
+  def __hash__(self):  # pylint: disable=useless-super-delegation
+    return super().__hash__()
+
+
+# Initialize the set of primitive types. These can be accessed by clients.
+BOOL = ValueKind('b')
+INT8 = ValueKind('i8')
+INT16 = ValueKind('i16')
+INT32 = ValueKind('i32')
+INT64 = ValueKind('i64')
+UINT8 = ValueKind('u8')
+UINT16 = ValueKind('u16')
+UINT32 = ValueKind('u32')
+UINT64 = ValueKind('u64')
+FLOAT = ValueKind('f')
+DOUBLE = ValueKind('d')
+NULLABLE_BOOL = ValueKind('?b', True)
+NULLABLE_INT8 = ValueKind('?i8', True)
+NULLABLE_INT16 = ValueKind('?i16', True)
+NULLABLE_INT32 = ValueKind('?i32', True)
+NULLABLE_INT64 = ValueKind('?i64', True)
+NULLABLE_UINT8 = ValueKind('?u8', True)
+NULLABLE_UINT16 = ValueKind('?u16', True)
+NULLABLE_UINT32 = ValueKind('?u32', True)
+NULLABLE_UINT64 = ValueKind('?u64', True)
+NULLABLE_FLOAT = ValueKind('?f', True)
+NULLABLE_DOUBLE = ValueKind('?d', True)
+STRING = ReferenceKind('s')
+HANDLE = ReferenceKind('h')
+DCPIPE = ReferenceKind('h:d:c')
+DPPIPE = ReferenceKind('h:d:p')
+MSGPIPE = ReferenceKind('h:m')
+SHAREDBUFFER = ReferenceKind('h:s')
+PLATFORMHANDLE = ReferenceKind('h:p')
+NULLABLE_STRING = ReferenceKind('?s', True)
+NULLABLE_HANDLE = ReferenceKind('?h', True)
+NULLABLE_DCPIPE = ReferenceKind('?h:d:c', True)
+NULLABLE_DPPIPE = ReferenceKind('?h:d:p', True)
+NULLABLE_MSGPIPE = ReferenceKind('?h:m', True)
+NULLABLE_SHAREDBUFFER = ReferenceKind('?h:s', True)
+NULLABLE_PLATFORMHANDLE = ReferenceKind('?h:p', True)
+
+# Collection of all Primitive types
+PRIMITIVES = (
+    BOOL,
+    INT8,
+    INT16,
+    INT32,
+    INT64,
+    UINT8,
+    UINT16,
+    UINT32,
+    UINT64,
+    FLOAT,
+    DOUBLE,
+    NULLABLE_BOOL,
+    NULLABLE_INT8,
+    NULLABLE_INT16,
+    NULLABLE_INT32,
+    NULLABLE_INT64,
+    NULLABLE_UINT8,
+    NULLABLE_UINT16,
+    NULLABLE_UINT32,
+    NULLABLE_UINT64,
+    NULLABLE_FLOAT,
+    NULLABLE_DOUBLE,
+    STRING,
+    HANDLE,
+    DCPIPE,
+    DPPIPE,
+    MSGPIPE,
+    SHAREDBUFFER,
+    PLATFORMHANDLE,
+    NULLABLE_STRING,
+    NULLABLE_HANDLE,
+    NULLABLE_DCPIPE,
+    NULLABLE_DPPIPE,
+    NULLABLE_MSGPIPE,
+    NULLABLE_SHAREDBUFFER,
+    NULLABLE_PLATFORMHANDLE,
+)
+
+ATTRIBUTE_MIN_VERSION = 'MinVersion'
+ATTRIBUTE_DEFAULT = 'Default'
+ATTRIBUTE_EXTENSIBLE = 'Extensible'
+ATTRIBUTE_NO_INTERRUPT = 'NoInterrupt'
+ATTRIBUTE_STABLE = 'Stable'
+ATTRIBUTE_SUPPORTS_URGENT = 'SupportsUrgent'
+ATTRIBUTE_SYNC = 'Sync'
+ATTRIBUTE_UNLIMITED_SIZE = 'UnlimitedSize'
+ATTRIBUTE_UUID = 'Uuid'
+ATTRIBUTE_SERVICE_SANDBOX = 'ServiceSandbox'
+ATTRIBUTE_REQUIRE_CONTEXT = 'RequireContext'
+ATTRIBUTE_ALLOWED_CONTEXT = 'AllowedContext'
+ATTRIBUTE_RUNTIME_FEATURE = 'RuntimeFeature'
+
+
+class NamedValue:
+  def __init__(self, module, parent_kind, mojom_name):
+    self.module = module
+    self.parent_kind = parent_kind
+    self.mojom_name = mojom_name
+
+  def GetSpec(self):
+    return (self.module.GetNamespacePrefix() +
+            (self.parent_kind and
+             (self.parent_kind.mojom_name + '.') or "") + self.mojom_name)
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, NamedValue)
+            and (self.parent_kind, self.mojom_name) == (rhs.parent_kind,
+                                                        rhs.mojom_name))
+
+  def __hash__(self):
+    return hash((self.parent_kind, self.mojom_name))
+
+
+class BuiltinValue:
+  def __init__(self, value):
+    self.value = value
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, BuiltinValue) and self.value == rhs.value
+
+
+class ConstantValue(NamedValue):
+  def __init__(self, module, parent_kind, constant):
+    NamedValue.__init__(self, module, parent_kind, constant.mojom_name)
+    self.constant = constant
+
+  @property
+  def name(self):
+    return self.constant.name
+
+
+class EnumValue(NamedValue):
+  def __init__(self, module, enum, field):
+    NamedValue.__init__(self, module, enum.parent_kind, field.mojom_name)
+    self.field = field
+    self.enum = enum
+
+  def GetSpec(self):
+    return (self.module.GetNamespacePrefix() +
+            (self.parent_kind and (self.parent_kind.mojom_name + '.') or "") +
+            self.enum.mojom_name + '.' + self.mojom_name)
+
+  @property
+  def name(self):
+    return self.field.name
+
+
+class Constant:
+  def __init__(self, mojom_name=None, kind=None, value=None, parent_kind=None):
+    self.mojom_name = mojom_name
+    self.name = None
+    self.kind = kind
+    self.value = value
+    self.parent_kind = parent_kind
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeConstant(self.mojom_name)
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, Constant)
+            and (self.mojom_name, self.kind, self.value,
+                 self.parent_kind) == (rhs.mojom_name, rhs.kind, rhs.value,
+                                       rhs.parent_kind))
+
+
+class Field:
+  def __init__(self,
+               mojom_name=None,
+               kind=None,
+               ordinal=None,
+               default=None,
+               attributes=None):
+    if self.__class__.__name__ == 'Field':
+      raise Exception()
+    self.mojom_name = mojom_name
+    self.name = None
+    self.kind = kind
+    self.ordinal = ordinal
+    self.default = default
+    self.attributes = attributes
+
+  def Repr(self, as_ref=True):
+    # pylint: disable=unused-argument
+    # Fields are only referenced by objects which define them and thus
+    # they are always displayed as non-references.
+    return GenericRepr(self, {'mojom_name': False, 'kind': True})
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeField(self.mojom_name)
+
+  @property
+  def min_version(self):
+    return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
+        if self.attributes else None
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, Field)
+            and (self.mojom_name, self.kind, self.ordinal, self.default,
+                 self.attributes) == (rhs.mojom_name, rhs.kind, rhs.ordinal,
+                                      rhs.default, rhs.attributes))
+
+  def __hash__(self):
+    return hash((self.mojom_name, self.kind, self.ordinal, self.default))
+
+
+class StructField(Field):
+  def __hash__(self):
+    return super(Field, self).__hash__()
+
+
+class UnionField(Field):
+  def __init__(self,
+               mojom_name=None,
+               kind=None,
+               ordinal=None,
+               default=None,
+               attributes=None):
+    Field.__init__(self, mojom_name, kind, ordinal, default, attributes)
+
+  @property
+  def is_default(self):
+    return self.attributes.get(ATTRIBUTE_DEFAULT, False) \
+        if self.attributes else False
+
+
+def _IsFieldBackwardCompatible(new_field, old_field, checker):
+  if (new_field.min_version or 0) != (old_field.min_version or 0):
+    return False
+
+  return checker.IsBackwardCompatible(new_field.kind, old_field.kind)
+
+
+class Feature(ReferenceKind):
+  """A runtime enabled feature defined from mojom.
+
+  Attributes:
+    mojom_name: {str} The name of the feature type as defined in mojom.
+    name: {str} The stylized name. (Note: not the "name" used by FeatureList.)
+    constants: {List[Constant]} The constants defined in the feature scope.
+    attributes: {dict} Additional information about the feature.
+  """
+
+  Kind.AddSharedProperty('mojom_name')
+  Kind.AddSharedProperty('name')
+  Kind.AddSharedProperty('constants')
+  Kind.AddSharedProperty('attributes')
+
+  def __init__(self, mojom_name=None, module=None, attributes=None):
+    if mojom_name is not None:
+      spec = 'x:' + mojom_name
+    else:
+      spec = None
+    ReferenceKind.__init__(self, spec, False, module)
+    self.mojom_name = mojom_name
+    self.name = None
+    self.constants = []
+    self.attributes = attributes
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeFeature(self.mojom_name)
+    for constant in self.constants:
+      constant.Stylize(stylizer)
+
+
+class Struct(ReferenceKind):
+  """A struct with typed fields.
+
+  Attributes:
+    mojom_name: {str} The name of the struct type as defined in mojom.
+    name: {str} The stylized name.
+    native_only: {bool} Does the struct have a body (i.e. any fields) or is it
+        purely a native struct.
+    custom_serializer: {bool} Should we generate a serializer for the struct or
+        will one be provided by non-generated code.
+    fields: {List[StructField]} The members of the struct.
+    enums: {List[Enum]} The enums defined in the struct scope.
+    constants: {List[Constant]} The constants defined in the struct scope.
+    attributes: {dict} Additional information about the struct, such as
+        if it's a native struct.
+  """
+
+  Kind.AddSharedProperty('mojom_name')
+  Kind.AddSharedProperty('name')
+  Kind.AddSharedProperty('native_only')
+  Kind.AddSharedProperty('custom_serializer')
+  Kind.AddSharedProperty('fields')
+  Kind.AddSharedProperty('enums')
+  Kind.AddSharedProperty('constants')
+  Kind.AddSharedProperty('attributes')
+
+  def __init__(self, mojom_name=None, module=None, attributes=None):
+    if mojom_name is not None:
+      spec = 'x:' + mojom_name
+    else:
+      spec = None
+    ReferenceKind.__init__(self, spec, False, module)
+    self.mojom_name = mojom_name
+    self.name = None
+    self.native_only = False
+    self.custom_serializer = False
+    self.fields = []
+    self.enums = []
+    self.constants = []
+    self.attributes = attributes
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s mojom_name=%r module=%s>' % (self.__class__.__name__,
+                                               self.mojom_name,
+                                               Repr(self.module, as_ref=True))
+    return GenericRepr(self, {
+        'mojom_name': False,
+        'fields': False,
+        'module': True
+    })
+
+  def AddField(self,
+               mojom_name,
+               kind,
+               ordinal=None,
+               default=None,
+               attributes=None):
+    field = StructField(mojom_name, kind, ordinal, default, attributes)
+    self.fields.append(field)
+    return field
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeStruct(self.mojom_name)
+    for field in self.fields:
+      field.Stylize(stylizer)
+    for enum in self.enums:
+      enum.Stylize(stylizer)
+    for constant in self.constants:
+      constant.Stylize(stylizer)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    """This struct is backward-compatible with rhs (older_struct) if and only if
+    all of the following conditions hold:
+      - Any newly added field is tagged with a [MinVersion] attribute specifying
+        a version number greater than all previously used [MinVersion]
+        attributes within the struct.
+      - All fields present in rhs remain present in the new struct,
+        with the same ordinal position, same optional or non-optional status,
+        same (or backward-compatible) type and where applicable, the same
+        [MinVersion] attribute value.
+      - All [MinVersion] attributes must be non-decreasing in ordinal order.
+      - All reference-typed (string, array, map, struct, or union) fields tagged
+        with a [MinVersion] greater than zero must be optional.
+    """
+
+    def buildOrdinalFieldMap(struct):
+      fields_by_ordinal = {}
+      for field in struct.fields:
+        if field.ordinal in fields_by_ordinal:
+          raise Exception('Multiple fields with ordinal %s in struct %s.' %
+                          (field.ordinal, struct.mojom_name))
+        fields_by_ordinal[field.ordinal] = field
+      return fields_by_ordinal
+
+    new_fields = buildOrdinalFieldMap(self)
+    old_fields = buildOrdinalFieldMap(rhs)
+    if len(new_fields) < len(old_fields):
+      # At least one field was removed, which is not OK.
+      return False
+
+    # If there are N fields, existing ordinal values must exactly cover the
+    # range from 0 to N-1.
+    num_old_ordinals = len(old_fields)
+    max_old_min_version = 0
+    for ordinal in range(num_old_ordinals):
+      new_field = new_fields[ordinal]
+      old_field = old_fields[ordinal]
+      if (old_field.min_version or 0) > max_old_min_version:
+        max_old_min_version = old_field.min_version
+      if not _IsFieldBackwardCompatible(new_field, old_field, checker):
+        # Type or min-version mismatch between old and new versions of the same
+        # ordinal field.
+        return False
+
+    # At this point we know all old fields are intact in the new struct
+    # definition. Now verify that all new fields have a high enough min version
+    # and are appropriately optional where required.
+    num_new_ordinals = len(new_fields)
+    last_min_version = max_old_min_version
+    for ordinal in range(num_old_ordinals, num_new_ordinals):
+      new_field = new_fields[ordinal]
+      min_version = new_field.min_version or 0
+      if min_version <= max_old_min_version:
+        # A new field is being added to an existing version, which is not OK.
+        return False
+      if min_version < last_min_version:
+        # The [MinVersion] of a field cannot be lower than the [MinVersion] of
+        # a field with lower ordinal value.
+        return False
+      if IsReferenceKind(new_field.kind) and not IsNullableKind(new_field.kind):
+        # New fields whose type can be nullable MUST be nullable.
+        return False
+
+    return True
+
+  @property
+  def stable(self):
+    return self.attributes.get(ATTRIBUTE_STABLE, False) \
+        if self.attributes else False
+
+  @property
+  def qualified_name(self):
+    if self.parent_kind:
+      prefix = self.parent_kind.qualified_name + '.'
+    else:
+      prefix = self.module.GetNamespacePrefix()
+    return '%s%s' % (prefix, self.mojom_name)
+
+  def _tuple(self):
+    return (self.mojom_name, self.native_only, self.fields, self.constants,
+            self.attributes)
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, Struct) and self._tuple() == rhs._tuple()
+
+  def __lt__(self, rhs):
+    if not isinstance(self, type(rhs)):
+      return str(type(self)) < str(type(rhs))
+
+    return self._tuple() < rhs._tuple()
+
+  def __hash__(self):
+    return id(self)
+
+
+class Union(ReferenceKind):
+  """A union of several kinds.
+
+  Attributes:
+    mojom_name: {str} The name of the union type as defined in mojom.
+    name: {str} The stylized name.
+    fields: {List[UnionField]} The members of the union.
+    attributes: {dict} Additional information about the union, such as
+        which Java class name to use to represent it in the generated
+        bindings.
+  """
+  Kind.AddSharedProperty('mojom_name')
+  Kind.AddSharedProperty('name')
+  Kind.AddSharedProperty('fields')
+  Kind.AddSharedProperty('attributes')
+  Kind.AddSharedProperty('default_field')
+
+  def __init__(self, mojom_name=None, module=None, attributes=None):
+    if mojom_name is not None:
+      spec = 'x:' + mojom_name
+    else:
+      spec = None
+    ReferenceKind.__init__(self, spec, False, module)
+    self.mojom_name = mojom_name
+    self.name = None
+    self.fields = []
+    self.attributes = attributes
+    self.default_field = None
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s spec=%r is_nullable=%r fields=%s>' % (
+          self.__class__.__name__, self.spec, self.is_nullable, Repr(
+              self.fields))
+    return GenericRepr(self, {'fields': True, 'is_nullable': False})
+
+  def AddField(self, mojom_name, kind, ordinal=None, attributes=None):
+    field = UnionField(mojom_name, kind, ordinal, None, attributes)
+    self.fields.append(field)
+    return field
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeUnion(self.mojom_name)
+    for field in self.fields:
+      field.Stylize(stylizer)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    """This union is backward-compatible with rhs (older_union) if and only if
+    all of the following conditions hold:
+      - Any newly added field is tagged with a [MinVersion] attribute specifying
+        a version number greater than all previously used [MinVersion]
+        attributes within the union.
+      - All fields present in rhs remain present in the new union,
+        with the same ordinal value, same optional or non-optional status,
+        same (or backward-compatible) type, and where applicable, the same
+        [MinVersion] attribute value.
+    """
+
+    def buildOrdinalFieldMap(union):
+      fields_by_ordinal = {}
+      for field in union.fields:
+        if field.ordinal in fields_by_ordinal:
+          raise Exception('Multiple fields with ordinal %s in union %s.' %
+                          (field.ordinal, union.mojom_name))
+        fields_by_ordinal[field.ordinal] = field
+      return fields_by_ordinal
+
+    new_fields = buildOrdinalFieldMap(self)
+    old_fields = buildOrdinalFieldMap(rhs)
+    if len(new_fields) < len(old_fields):
+      # At least one field was removed, which is not OK.
+      return False
+
+    max_old_min_version = 0
+    for ordinal, old_field in old_fields.items():
+      new_field = new_fields.get(ordinal)
+      if not new_field:
+        # A field was removed, which is not OK.
+        return False
+      if not _IsFieldBackwardCompatible(new_field, old_field, checker):
+        # An field changed its type or MinVersion, which is not OK.
+        return False
+      old_min_version = old_field.min_version or 0
+      if old_min_version > max_old_min_version:
+        max_old_min_version = old_min_version
+
+    new_ordinals = set(new_fields.keys()) - set(old_fields.keys())
+    for ordinal in new_ordinals:
+      if (new_fields[ordinal].min_version or 0) <= max_old_min_version:
+        # New fields must use a MinVersion greater than any old fields.
+        return False
+
+    return True
+
+  @property
+  def extensible(self):
+    return self.attributes.get(ATTRIBUTE_EXTENSIBLE, False) \
+        if self.attributes else False
+
+  @property
+  def stable(self):
+    return self.attributes.get(ATTRIBUTE_STABLE, False) \
+        if self.attributes else False
+
+  @property
+  def qualified_name(self):
+    if self.parent_kind:
+      prefix = self.parent_kind.qualified_name + '.'
+    else:
+      prefix = self.module.GetNamespacePrefix()
+    return '%s%s' % (prefix, self.mojom_name)
+
+  def _tuple(self):
+    return (self.mojom_name, self.fields, self.attributes)
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, Union) and self._tuple() == rhs._tuple()
+
+  def __lt__(self, rhs):
+    if not isinstance(self, type(rhs)):
+      return str(type(self)) < str(type(rhs))
+
+    return self._tuple() < rhs._tuple()
+
+  def __hash__(self):
+    return id(self)
+
+
+class Array(ReferenceKind):
+  """An array.
+
+  Attributes:
+    kind: {Kind} The type of the elements. May be None.
+    length: The number of elements. None if unknown.
+  """
+
+  Kind.AddSharedProperty('kind')
+  Kind.AddSharedProperty('length')
+
+  def __init__(self, kind=None, length=None):
+    if kind is not None:
+      if length is not None:
+        spec = 'a%d:%s' % (length, kind.spec)
+      else:
+        spec = 'a:%s' % kind.spec
+
+      ReferenceKind.__init__(self, spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+    self.length = length
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s spec=%r is_nullable=%r kind=%s length=%r>' % (
+          self.__class__.__name__, self.spec, self.is_nullable, Repr(
+              self.kind), self.length)
+    return GenericRepr(self, {
+        'kind': True,
+        'length': False,
+        'is_nullable': False
+    })
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, Array)
+            and (self.kind, self.length) == (rhs.kind, rhs.length))
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return (isinstance(rhs, Array) and self.length == rhs.length
+            and checker.IsBackwardCompatible(self.kind, rhs.kind))
+
+
+class Map(ReferenceKind):
+  """A map.
+
+  Attributes:
+    key_kind: {Kind} The type of the keys. May be None.
+    value_kind: {Kind} The type of the elements. May be None.
+  """
+  Kind.AddSharedProperty('key_kind')
+  Kind.AddSharedProperty('value_kind')
+
+  def __init__(self, key_kind=None, value_kind=None):
+    if (key_kind is not None and value_kind is not None):
+      ReferenceKind.__init__(
+          self, 'm[' + key_kind.spec + '][' + value_kind.spec + ']')
+      if IsNullableKind(key_kind):
+        raise Exception("Nullable kinds cannot be keys in maps.")
+      if IsAnyHandleKind(key_kind):
+        raise Exception("Handles cannot be keys in maps.")
+      if IsAnyInterfaceKind(key_kind):
+        raise Exception("Interfaces cannot be keys in maps.")
+      if IsArrayKind(key_kind):
+        raise Exception("Arrays cannot be keys in maps.")
+    else:
+      ReferenceKind.__init__(self)
+
+    self.key_kind = key_kind
+    self.value_kind = value_kind
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s spec=%r is_nullable=%r key_kind=%s value_kind=%s>' % (
+          self.__class__.__name__, self.spec, self.is_nullable,
+          Repr(self.key_kind), Repr(self.value_kind))
+    return GenericRepr(self, {'key_kind': True, 'value_kind': True})
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, Map) and
+            (self.key_kind, self.value_kind) == (rhs.key_kind, rhs.value_kind))
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return (isinstance(rhs, Map)
+            and checker.IsBackwardCompatible(self.key_kind, rhs.key_kind)
+            and checker.IsBackwardCompatible(self.value_kind, rhs.value_kind))
+
+
+class PendingRemote(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, Interface):
+        raise Exception(
+            'pending_remote<T> requires T to be an interface type. Got %r' %
+            kind.spec)
+      ReferenceKind.__init__(self, 'rmt:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, PendingRemote) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return (isinstance(rhs, PendingRemote)
+            and checker.IsBackwardCompatible(self.kind, rhs.kind))
+
+
+class PendingReceiver(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, Interface):
+        raise Exception(
+            'pending_receiver<T> requires T to be an interface type. Got %r' %
+            kind.spec)
+      ReferenceKind.__init__(self, 'rcv:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, PendingReceiver) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return isinstance(rhs, PendingReceiver) and checker.IsBackwardCompatible(
+        self.kind, rhs.kind)
+
+
+class PendingAssociatedRemote(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, Interface):
+        raise Exception(
+            'pending_associated_remote<T> requires T to be an interface ' +
+            'type. Got %r' % kind.spec)
+      ReferenceKind.__init__(self, 'rma:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, PendingAssociatedRemote) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return isinstance(rhs,
+                      PendingAssociatedRemote) and checker.IsBackwardCompatible(
+                          self.kind, rhs.kind)
+
+
+class PendingAssociatedReceiver(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, Interface):
+        raise Exception(
+            'pending_associated_receiver<T> requires T to be an interface' +
+            'type. Got %r' % kind.spec)
+      ReferenceKind.__init__(self, 'rca:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, PendingAssociatedReceiver) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return isinstance(
+        rhs, PendingAssociatedReceiver) and checker.IsBackwardCompatible(
+            self.kind, rhs.kind)
+
+
+class InterfaceRequest(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, Interface):
+        raise Exception(
+            "Interface request requires %r to be an interface." % kind.spec)
+      ReferenceKind.__init__(self, 'r:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, InterfaceRequest) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return isinstance(rhs, InterfaceRequest) and checker.IsBackwardCompatible(
+        self.kind, rhs.kind)
+
+
+class AssociatedInterfaceRequest(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, InterfaceRequest):
+        raise Exception(
+            "Associated interface request requires %r to be an interface "
+            "request." % kind.spec)
+      assert not kind.is_nullable
+      ReferenceKind.__init__(self, 'asso:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind.kind if kind is not None else None
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, AssociatedInterfaceRequest) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return isinstance(
+        rhs, AssociatedInterfaceRequest) and checker.IsBackwardCompatible(
+            self.kind, rhs.kind)
+
+
+class Parameter:
+  def __init__(self,
+               mojom_name=None,
+               kind=None,
+               ordinal=None,
+               default=None,
+               attributes=None):
+    self.mojom_name = mojom_name
+    self.name = None
+    self.ordinal = ordinal
+    self.kind = kind
+    self.default = default
+    self.attributes = attributes
+
+  def Repr(self, as_ref=True):
+    # pylint: disable=unused-argument
+    return '<%s mojom_name=%r kind=%s>' % (
+        self.__class__.__name__, self.mojom_name, self.kind.Repr(as_ref=True))
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeParameter(self.mojom_name)
+
+  @property
+  def min_version(self):
+    return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
+        if self.attributes else None
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, Parameter)
+            and (self.mojom_name, self.ordinal, self.kind, self.default,
+                 self.attributes) == (rhs.mojom_name, rhs.ordinal, rhs.kind,
+                                      rhs.default, rhs.attributes))
+
+
+class Method:
+  def __init__(self, interface, mojom_name, ordinal=None, attributes=None):
+    self.interface = interface
+    self.mojom_name = mojom_name
+    self.name = None
+    self.explicit_ordinal = ordinal
+    self.ordinal = ordinal
+    self.parameters = []
+    self.param_struct = None
+    self.response_parameters = None
+    self.response_param_struct = None
+    self.attributes = attributes
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s mojom_name=%r>' % (self.__class__.__name__, self.mojom_name)
+    return GenericRepr(self, {
+        'mojom_name': False,
+        'parameters': True,
+        'response_parameters': True
+    })
+
+  def AddParameter(self,
+                   mojom_name,
+                   kind,
+                   ordinal=None,
+                   default=None,
+                   attributes=None):
+    parameter = Parameter(mojom_name, kind, ordinal, default, attributes)
+    self.parameters.append(parameter)
+    return parameter
+
+  def AddResponseParameter(self,
+                           mojom_name,
+                           kind,
+                           ordinal=None,
+                           default=None,
+                           attributes=None):
+    if self.response_parameters == None:
+      self.response_parameters = []
+    parameter = Parameter(mojom_name, kind, ordinal, default, attributes)
+    self.response_parameters.append(parameter)
+    return parameter
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeMethod(self.mojom_name)
+    for param in self.parameters:
+      param.Stylize(stylizer)
+    if self.response_parameters is not None:
+      for param in self.response_parameters:
+        param.Stylize(stylizer)
+
+    if self.param_struct:
+      self.param_struct.Stylize(stylizer)
+    if self.response_param_struct:
+      self.response_param_struct.Stylize(stylizer)
+
+  @property
+  def min_version(self):
+    return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
+        if self.attributes else None
+
+  @property
+  def sync(self):
+    return self.attributes.get(ATTRIBUTE_SYNC) \
+        if self.attributes else None
+
+  @property
+  def allow_interrupt(self):
+    return not self.attributes.get(ATTRIBUTE_NO_INTERRUPT) \
+        if self.attributes else True
+
+  @property
+  def unlimited_message_size(self):
+    return self.attributes.get(ATTRIBUTE_UNLIMITED_SIZE) \
+        if self.attributes else False
+
+  @property
+  def allowed_context(self):
+    return self.attributes.get(ATTRIBUTE_ALLOWED_CONTEXT) \
+        if self.attributes else None
+
+  @property
+  def supports_urgent(self):
+    return self.attributes.get(ATTRIBUTE_SUPPORTS_URGENT) \
+        if self.attributes else None
+
+  @property
+  def runtime_feature(self):
+    if not self.attributes:
+      return None
+    runtime_feature = self.attributes.get(ATTRIBUTE_RUNTIME_FEATURE, None)
+    if runtime_feature is None:
+      return None
+    if not isinstance(runtime_feature, Feature):
+      raise Exception("RuntimeFeature attribute on %s must be a feature." %
+                      self.name)
+    return runtime_feature
+
+  def _tuple(self):
+    return (self.mojom_name, self.ordinal, self.parameters,
+            self.response_parameters, self.attributes)
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, Method) and self._tuple() == rhs._tuple()
+
+  def __lt__(self, rhs):
+    if not isinstance(self, type(rhs)):
+      return str(type(self)) < str(type(rhs))
+
+    return self._tuple() < rhs._tuple()
+
+
+class Interface(ReferenceKind):
+  Kind.AddSharedProperty('mojom_name')
+  Kind.AddSharedProperty('name')
+  Kind.AddSharedProperty('methods')
+  Kind.AddSharedProperty('enums')
+  Kind.AddSharedProperty('constants')
+  Kind.AddSharedProperty('attributes')
+
+  def __init__(self, mojom_name=None, module=None, attributes=None):
+    if mojom_name is not None:
+      spec = 'x:' + mojom_name
+    else:
+      spec = None
+    ReferenceKind.__init__(self, spec, False, module)
+    self.mojom_name = mojom_name
+    self.name = None
+    self.methods = []
+    self.enums = []
+    self.constants = []
+    self.attributes = attributes
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s mojom_name=%r>' % (self.__class__.__name__, self.mojom_name)
+    return GenericRepr(self, {
+        'mojom_name': False,
+        'attributes': False,
+        'methods': False
+    })
+
+  def AddMethod(self, mojom_name, ordinal=None, attributes=None):
+    method = Method(self, mojom_name, ordinal, attributes)
+    self.methods.append(method)
+    return method
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeInterface(self.mojom_name)
+    for method in self.methods:
+      method.Stylize(stylizer)
+    for enum in self.enums:
+      enum.Stylize(stylizer)
+    for constant in self.constants:
+      constant.Stylize(stylizer)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    """This interface is backward-compatible with rhs (older_interface) if and
+    only if all of the following conditions hold:
+      - All defined methods in rhs (when identified by ordinal) have
+        backward-compatible definitions in this interface. For each method this
+        means:
+          - The parameter list is backward-compatible, according to backward-
+            compatibility rules for structs, where each parameter is essentially
+            a struct field.
+          - If the old method definition does not specify a reply message, the
+            new method definition must not specify a reply message.
+          - If the old method definition specifies a reply message, the new
+            method definition must also specify a reply message with a parameter
+            list that is backward-compatible according to backward-compatibility
+            rules for structs.
+      - All newly introduced methods in this interface have a [MinVersion]
+        attribute specifying a version greater than any method in
+        rhs.
+    """
+
+    def buildOrdinalMethodMap(interface):
+      methods_by_ordinal = {}
+      for method in interface.methods:
+        if method.ordinal in methods_by_ordinal:
+          raise Exception('Multiple methods with ordinal %s in interface %s.' %
+                          (method.ordinal, interface.mojom_name))
+        methods_by_ordinal[method.ordinal] = method
+      return methods_by_ordinal
+
+    new_methods = buildOrdinalMethodMap(self)
+    old_methods = buildOrdinalMethodMap(rhs)
+    max_old_min_version = 0
+    for ordinal, old_method in old_methods.items():
+      new_method = new_methods.get(ordinal)
+      if not new_method:
+        # A method was removed, which is not OK.
+        return False
+
+      if not checker.IsBackwardCompatible(new_method.param_struct,
+                                          old_method.param_struct):
+        # The parameter list is not backward-compatible, which is not OK.
+        return False
+
+      if old_method.response_param_struct is None:
+        if new_method.response_param_struct is not None:
+          # A reply was added to a message which didn't have one before, and
+          # this is not OK.
+          return False
+      else:
+        if new_method.response_param_struct is None:
+          # A reply was removed from a message, which is not OK.
+          return False
+        if not checker.IsBackwardCompatible(new_method.response_param_struct,
+                                            old_method.response_param_struct):
+          # The new message's reply is not backward-compatible with the old
+          # message's reply, which is not OK.
+          return False
+
+      if (old_method.min_version or 0) > max_old_min_version:
+        max_old_min_version = old_method.min_version
+
+    # All the old methods are compatible with their new counterparts. Now verify
+    # that newly added methods are properly versioned.
+    new_ordinals = set(new_methods.keys()) - set(old_methods.keys())
+    for ordinal in new_ordinals:
+      new_method = new_methods[ordinal]
+      if (new_method.min_version or 0) <= max_old_min_version:
+        # A method was added to an existing version, which is not OK.
+        return False
+
+    return True
+
+  @property
+  def service_sandbox(self):
+    if not self.attributes:
+      return None
+    service_sandbox = self.attributes.get(ATTRIBUTE_SERVICE_SANDBOX, None)
+    if service_sandbox is None:
+      return None
+    # Constants are only allowed to refer to an enum here, so replace.
+    if isinstance(service_sandbox, Constant):
+      service_sandbox = service_sandbox.value
+    if not isinstance(service_sandbox, EnumValue):
+      raise Exception("ServiceSandbox attribute on %s must be an enum value." %
+                      self.module.name)
+    return service_sandbox
+
+  @property
+  def runtime_feature(self):
+    if not self.attributes:
+      return None
+    runtime_feature = self.attributes.get(ATTRIBUTE_RUNTIME_FEATURE, None)
+    if runtime_feature is None:
+      return None
+    if not isinstance(runtime_feature, Feature):
+      raise Exception("RuntimeFeature attribute on %s must be a feature." %
+                      self.name)
+    return runtime_feature
+
+  @property
+  def require_context(self):
+    if not self.attributes:
+      return None
+    return self.attributes.get(ATTRIBUTE_REQUIRE_CONTEXT, None)
+
+  @property
+  def stable(self):
+    return self.attributes.get(ATTRIBUTE_STABLE, False) \
+        if self.attributes else False
+
+  @property
+  def qualified_name(self):
+    if self.parent_kind:
+      prefix = self.parent_kind.qualified_name + '.'
+    else:
+      prefix = self.module.GetNamespacePrefix()
+    return '%s%s' % (prefix, self.mojom_name)
+
+  def _tuple(self):
+    return (self.mojom_name, self.methods, self.enums, self.constants,
+            self.attributes)
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, Interface) and self._tuple() == rhs._tuple()
+
+  def __lt__(self, rhs):
+    if not isinstance(self, type(rhs)):
+      return str(type(self)) < str(type(rhs))
+
+    return self._tuple() < rhs._tuple()
+
+  @property
+  def uuid(self):
+    uuid_str = self.attributes.get(ATTRIBUTE_UUID) if self.attributes else None
+    if uuid_str is None:
+      return None
+
+    try:
+      u = UUID(uuid_str)
+    except:
+      raise ValueError('Invalid format for Uuid attribute on interface {}. '
+                       'Expected standard RFC 4122 string representation of '
+                       'a UUID.'.format(self.mojom_name))
+    return (int(u.hex[:16], 16), int(u.hex[16:], 16))
+
+  def __hash__(self):
+    return id(self)
+
+
+class AssociatedInterface(ReferenceKind):
+  Kind.AddSharedProperty('kind')
+
+  def __init__(self, kind=None):
+    if kind is not None:
+      if not isinstance(kind, Interface):
+        raise Exception(
+            "Associated interface requires %r to be an interface." % kind.spec)
+      assert not kind.is_nullable
+      ReferenceKind.__init__(self, 'asso:' + kind.spec)
+    else:
+      ReferenceKind.__init__(self)
+    self.kind = kind
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, AssociatedInterface) and self.kind == rhs.kind
+
+  def __hash__(self):
+    return id(self)
+
+  def IsBackwardCompatible(self, rhs, checker):
+    return isinstance(rhs,
+                      AssociatedInterface) and checker.IsBackwardCompatible(
+                          self.kind, rhs.kind)
+
+
+class EnumField:
+  def __init__(self,
+               mojom_name=None,
+               value=None,
+               attributes=None,
+               numeric_value=None):
+    self.mojom_name = mojom_name
+    self.name = None
+    self.value = value
+    self.attributes = attributes
+    self.numeric_value = numeric_value
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeEnumField(self.mojom_name)
+
+  @property
+  def default(self):
+    return self.attributes.get(ATTRIBUTE_DEFAULT, False) \
+        if self.attributes else False
+
+  @property
+  def min_version(self):
+    return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
+        if self.attributes else None
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, EnumField)
+            and (self.mojom_name, self.value, self.attributes,
+                 self.numeric_value) == (rhs.mojom_name, rhs.value,
+                                         rhs.attributes, rhs.numeric_value))
+
+
+class Enum(ValueKind):
+  Kind.AddSharedProperty('mojom_name')
+  Kind.AddSharedProperty('name')
+  Kind.AddSharedProperty('native_only')
+  Kind.AddSharedProperty('fields')
+  Kind.AddSharedProperty('attributes')
+  Kind.AddSharedProperty('min_value')
+  Kind.AddSharedProperty('max_value')
+  Kind.AddSharedProperty('default_field')
+
+  def __init__(self, mojom_name=None, module=None, attributes=None):
+    if mojom_name is not None:
+      spec = 'x:' + mojom_name
+    else:
+      spec = None
+    ValueKind.__init__(self, spec, False, module)
+    self.mojom_name = mojom_name
+    self.name = None
+    self.native_only = False
+    self.fields = []
+    self.attributes = attributes
+    self.min_value = None
+    self.max_value = None
+    self.default_field = None
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s mojom_name=%r>' % (self.__class__.__name__, self.mojom_name)
+    return GenericRepr(self, {'mojom_name': False, 'fields': False})
+
+  def Stylize(self, stylizer):
+    self.name = stylizer.StylizeEnum(self.mojom_name)
+    for field in self.fields:
+      field.Stylize(stylizer)
+
+  @property
+  def extensible(self):
+    return self.attributes.get(ATTRIBUTE_EXTENSIBLE, False) \
+        if self.attributes else False
+
+  @property
+  def stable(self):
+    return self.attributes.get(ATTRIBUTE_STABLE, False) \
+        if self.attributes else False
+
+  @property
+  def qualified_name(self):
+    if self.parent_kind:
+      prefix = self.parent_kind.qualified_name + '.'
+    else:
+      prefix = self.module.GetNamespacePrefix()
+    return '%s%s' % (prefix, self.mojom_name)
+
+  # pylint: disable=unused-argument
+  def IsBackwardCompatible(self, rhs, checker):
+    """This enum is backward-compatible with rhs (older_enum) if and only if one
+    of the following conditions holds:
+        - Neither enum is [Extensible] and both have the exact same set of valid
+          numeric values. Field names and aliases for the same numeric value do
+          not affect compatibility.
+        - rhs is [Extensible], and for every version defined by
+          rhs, this enum has the exact same set of valid numeric values.
+    """
+
+    def buildVersionFieldMap(enum):
+      fields_by_min_version = {}
+      for field in enum.fields:
+        if field.min_version not in fields_by_min_version:
+          fields_by_min_version[field.min_version] = set()
+        fields_by_min_version[field.min_version].add(field.numeric_value)
+      return fields_by_min_version
+
+    old_fields = buildVersionFieldMap(rhs)
+    new_fields = buildVersionFieldMap(self)
+
+    if new_fields.keys() != old_fields.keys() and not rhs.extensible:
+      raise Exception("Non-extensible enum cannot be modified")
+
+    for min_version, valid_values in old_fields.items():
+      if min_version not in new_fields:
+        raise Exception('New values added to an extensible enum '
+                        'do not specify MinVersion: %s' % new_fields)
+
+      if (new_fields[min_version] != valid_values):
+        if (len(new_fields[min_version]) < len(valid_values)):
+          raise Exception('Removing values for an existing MinVersion %s '
+                          'is not allowed' % min_version)
+
+        raise Exception(
+            'New values don\'t match old values'
+            'for an existing MinVersion %s,'
+            ' please specify MinVersion equal to "Next version" '
+            'in the enum description'
+            ' for the following values:\n%s' %
+            (min_version, new_fields[min_version].difference(valid_values)))
+    return True
+
+  def _tuple(self):
+    return (self.mojom_name, self.native_only, self.fields, self.attributes,
+            self.min_value, self.max_value, self.default_field)
+
+  def __eq__(self, rhs):
+    return isinstance(rhs, Enum) and self._tuple() == rhs._tuple()
+
+  def __lt__(self, rhs):
+    if not isinstance(self, type(rhs)):
+      return str(type(self)) < str(type(rhs))
+
+    return self._tuple() < rhs._tuple()
+
+  def __hash__(self):
+    return id(self)
+
+
+class Module:
+  def __init__(self, path=None, mojom_namespace=None, attributes=None):
+    self.path = path
+    self.mojom_namespace = mojom_namespace
+    self.namespace = None
+    self.structs = []
+    self.unions = []
+    self.interfaces = []
+    self.enums = []
+    self.features = []
+    self.constants = []
+    self.kinds = OrderedDict()
+    self.attributes = attributes
+    self.imports = []
+    self.imported_kinds = OrderedDict()
+    self.metadata = OrderedDict()
+
+  def __repr__(self):
+    # Gives us a decent __repr__ for modules.
+    return self.Repr()
+
+  def __eq__(self, rhs):
+    return (isinstance(rhs, Module)
+            and (self.path, self.attributes, self.mojom_namespace, self.imports,
+                 self.constants, self.enums, self.structs, self.unions,
+                 self.interfaces, self.features)
+            == (rhs.path, rhs.attributes, rhs.mojom_namespace, rhs.imports,
+                rhs.constants, rhs.enums, rhs.structs, rhs.unions,
+                rhs.interfaces, rhs.features))
+
+  def __hash__(self):
+    return id(self)
+
+  def Repr(self, as_ref=True):
+    if as_ref:
+      return '<%s path=%r mojom_namespace=%r>' % (
+          self.__class__.__name__, self.path, self.mojom_namespace)
+    return GenericRepr(
+        self, {
+            'path': False,
+            'mojom_namespace': False,
+            'attributes': False,
+            'structs': False,
+            'interfaces': False,
+            'unions': False,
+            'features': False,
+        })
+
+  def GetNamespacePrefix(self):
+    return '%s.' % self.mojom_namespace if self.mojom_namespace else ''
+
+  def AddInterface(self, mojom_name, attributes=None):
+    interface = Interface(mojom_name, self, attributes)
+    self.interfaces.append(interface)
+    return interface
+
+  def AddStruct(self, mojom_name, attributes=None):
+    struct = Struct(mojom_name, self, attributes)
+    self.structs.append(struct)
+    return struct
+
+  def AddUnion(self, mojom_name, attributes=None):
+    union = Union(mojom_name, self, attributes)
+    self.unions.append(union)
+    return union
+
+  def AddFeature(self, mojom_name, attributes=None):
+    feature = Feature(mojom_name, self, attributes)
+    self.features.append(feature)
+    return feature
+
+  def Stylize(self, stylizer):
+    self.namespace = stylizer.StylizeModule(self.mojom_namespace)
+    for struct in self.structs:
+      struct.Stylize(stylizer)
+    for union in self.unions:
+      union.Stylize(stylizer)
+    for interface in self.interfaces:
+      interface.Stylize(stylizer)
+    for enum in self.enums:
+      enum.Stylize(stylizer)
+    for constant in self.constants:
+      constant.Stylize(stylizer)
+    for feature in self.features:
+      feature.Stylize(stylizer)
+
+    for imported_module in self.imports:
+      imported_module.Stylize(stylizer)
+
+  def Dump(self, f):
+    pickle.dump(self, f)
+
+  @classmethod
+  def Load(cls, f):
+    result = pickle.load(f)
+    assert isinstance(result, Module)
+    return result
+
+
+def IsBoolKind(kind):
+  return kind.spec == BOOL.spec or kind.spec == NULLABLE_BOOL.spec
+
+
+def IsFloatKind(kind):
+  return kind.spec == FLOAT.spec or kind.spec == NULLABLE_FLOAT.spec
+
+
+def IsDoubleKind(kind):
+  return kind.spec == DOUBLE.spec or kind.spec == NULLABLE_DOUBLE.spec
+
+
+def IsIntegralKind(kind):
+  return (kind.spec == BOOL.spec or kind.spec == INT8.spec
+          or kind.spec == INT16.spec or kind.spec == INT32.spec
+          or kind.spec == INT64.spec or kind.spec == UINT8.spec
+          or kind.spec == UINT16.spec or kind.spec == UINT32.spec
+          or kind.spec == UINT64.spec or kind.spec == NULLABLE_BOOL.spec
+          or kind.spec == NULLABLE_INT8.spec or kind.spec == NULLABLE_INT16.spec
+          or kind.spec == NULLABLE_INT32.spec
+          or kind.spec == NULLABLE_INT64.spec
+          or kind.spec == NULLABLE_UINT8.spec
+          or kind.spec == NULLABLE_UINT16.spec
+          or kind.spec == NULLABLE_UINT32.spec
+          or kind.spec == NULLABLE_UINT64.spec)
+
+
+def IsStringKind(kind):
+  return kind.spec == STRING.spec or kind.spec == NULLABLE_STRING.spec
+
+
+def IsGenericHandleKind(kind):
+  return kind.spec == HANDLE.spec or kind.spec == NULLABLE_HANDLE.spec
+
+
+def IsDataPipeConsumerKind(kind):
+  return kind.spec == DCPIPE.spec or kind.spec == NULLABLE_DCPIPE.spec
+
+
+def IsDataPipeProducerKind(kind):
+  return kind.spec == DPPIPE.spec or kind.spec == NULLABLE_DPPIPE.spec
+
+
+def IsMessagePipeKind(kind):
+  return kind.spec == MSGPIPE.spec or kind.spec == NULLABLE_MSGPIPE.spec
+
+
+def IsSharedBufferKind(kind):
+  return (kind.spec == SHAREDBUFFER.spec
+          or kind.spec == NULLABLE_SHAREDBUFFER.spec)
+
+
+def IsPlatformHandleKind(kind):
+  return (kind.spec == PLATFORMHANDLE.spec
+          or kind.spec == NULLABLE_PLATFORMHANDLE.spec)
+
+
+def IsStructKind(kind):
+  return isinstance(kind, Struct)
+
+
+def IsUnionKind(kind):
+  return isinstance(kind, Union)
+
+
+def IsArrayKind(kind):
+  return isinstance(kind, Array)
+
+
+def IsFeatureKind(kind):
+  return isinstance(kind, Feature)
+
+
+def IsInterfaceKind(kind):
+  return isinstance(kind, Interface)
+
+
+def IsAssociatedInterfaceKind(kind):
+  return isinstance(kind, AssociatedInterface)
+
+
+def IsInterfaceRequestKind(kind):
+  return isinstance(kind, InterfaceRequest)
+
+
+def IsAssociatedInterfaceRequestKind(kind):
+  return isinstance(kind, AssociatedInterfaceRequest)
+
+
+def IsPendingRemoteKind(kind):
+  return isinstance(kind, PendingRemote)
+
+
+def IsPendingReceiverKind(kind):
+  return isinstance(kind, PendingReceiver)
+
+
+def IsPendingAssociatedRemoteKind(kind):
+  return isinstance(kind, PendingAssociatedRemote)
+
+
+def IsPendingAssociatedReceiverKind(kind):
+  return isinstance(kind, PendingAssociatedReceiver)
+
+
+def IsEnumKind(kind):
+  return isinstance(kind, Enum)
+
+
+def IsValueKind(kind):
+  return isinstance(kind, ValueKind)
+
+
+def IsReferenceKind(kind):
+  return isinstance(kind, ReferenceKind)
+
+
+def IsNullableKind(kind):
+  return kind.is_nullable
+
+
+def IsMapKind(kind):
+  return isinstance(kind, Map)
+
+
+def IsObjectKind(kind):
+  return IsPointerKind(kind) or IsUnionKind(kind)
+
+
+def IsPointerKind(kind):
+  return (IsStructKind(kind) or IsArrayKind(kind) or IsStringKind(kind)
+          or IsMapKind(kind))
+
+
+# Please note that it doesn't include any interface kind.
+def IsAnyHandleKind(kind):
+  return (IsGenericHandleKind(kind) or IsDataPipeConsumerKind(kind)
+          or IsDataPipeProducerKind(kind) or IsMessagePipeKind(kind)
+          or IsSharedBufferKind(kind) or IsPlatformHandleKind(kind))
+
+
+def IsAnyInterfaceKind(kind):
+  return (IsInterfaceKind(kind) or IsInterfaceRequestKind(kind)
+          or IsAssociatedKind(kind) or IsPendingRemoteKind(kind)
+          or IsPendingReceiverKind(kind))
+
+
+def IsAnyHandleOrInterfaceKind(kind):
+  return IsAnyHandleKind(kind) or IsAnyInterfaceKind(kind)
+
+
+def IsAssociatedKind(kind):
+  return (IsAssociatedInterfaceKind(kind)
+          or IsAssociatedInterfaceRequestKind(kind)
+          or IsPendingAssociatedRemoteKind(kind)
+          or IsPendingAssociatedReceiverKind(kind))
+
+
+def HasCallbacks(interface):
+  for method in interface.methods:
+    if method.response_parameters != None:
+      return True
+  return False
+
+
+# Finds out whether an interface passes associated interfaces and associated
+# interface requests.
+def PassesAssociatedKinds(interface):
+  visited_kinds = set()
+  for method in interface.methods:
+    if MethodPassesAssociatedKinds(method, visited_kinds):
+      return True
+  return False
+
+
+def _AnyMethodParameterRecursive(method, predicate, visited_kinds=None):
+  def _HasProperty(kind):
+    if kind in visited_kinds:
+      # No need to examine the kind again.
+      return False
+    visited_kinds.add(kind)
+    if predicate(kind):
+      return True
+    if IsArrayKind(kind):
+      return _HasProperty(kind.kind)
+    if IsStructKind(kind) or IsUnionKind(kind):
+      for field in kind.fields:
+        if _HasProperty(field.kind):
+          return True
+    if IsMapKind(kind):
+      if _HasProperty(kind.key_kind) or _HasProperty(kind.value_kind):
+        return True
+    return False
+
+  if visited_kinds is None:
+    visited_kinds = set()
+
+  for param in method.parameters:
+    if _HasProperty(param.kind):
+      return True
+  if method.response_parameters != None:
+    for param in method.response_parameters:
+      if _HasProperty(param.kind):
+        return True
+  return False
+
+
+# Finds out whether a method passes associated interfaces and associated
+# interface requests.
+def MethodPassesAssociatedKinds(method, visited_kinds=None):
+  return _AnyMethodParameterRecursive(
+      method, IsAssociatedKind, visited_kinds=visited_kinds)
+
+
+# Determines whether a method passes interfaces.
+def MethodPassesInterfaces(method):
+  return _AnyMethodParameterRecursive(method, IsInterfaceKind)
+
+
+def GetSyncMethodOrdinals(interface):
+  return [method.ordinal for method in interface.methods if method.sync]
+
+
+def HasUninterruptableMethods(interface):
+  for method in interface.methods:
+    if not method.allow_interrupt:
+      return True
+  return False
+
+
+def ContainsHandlesOrInterfaces(kind):
+  """Check if the kind contains any handles.
+
+  This check is recursive so it checks all struct fields, containers elements,
+  etc.
+
+  Args:
+    struct: {Kind} The kind to check.
+
+  Returns:
+    {bool}: True if the kind contains handles.
+  """
+  # We remember the types we already checked to avoid infinite recursion when
+  # checking recursive (or mutually recursive) types:
+  checked = set()
+
+  def Check(kind):
+    if kind.spec in checked:
+      return False
+    checked.add(kind.spec)
+    if IsStructKind(kind):
+      return any(Check(field.kind) for field in kind.fields)
+    if IsUnionKind(kind):
+      return any(Check(field.kind) for field in kind.fields)
+    if IsAnyHandleKind(kind):
+      return True
+    if IsAnyInterfaceKind(kind):
+      return True
+    if IsArrayKind(kind):
+      return Check(kind.kind)
+    if IsMapKind(kind):
+      return Check(kind.key_kind) or Check(kind.value_kind)
+    return False
+
+  return Check(kind)
+
+
+def ContainsNativeTypes(kind):
+  """Check if the kind contains any native type (struct or enum).
+
+  This check is recursive so it checks all struct fields, scoped interface
+  enums, etc.
+
+  Args:
+    struct: {Kind} The kind to check.
+
+  Returns:
+    {bool}: True if the kind contains native types.
+  """
+  # We remember the types we already checked to avoid infinite recursion when
+  # checking recursive (or mutually recursive) types:
+  checked = set()
+
+  def Check(kind):
+    if kind.spec in checked:
+      return False
+    checked.add(kind.spec)
+    if IsEnumKind(kind):
+      return kind.native_only
+    if IsStructKind(kind):
+      if kind.native_only:
+        return True
+      if any(enum.native_only for enum in kind.enums):
+        return True
+      return any(Check(field.kind) for field in kind.fields)
+    if IsUnionKind(kind):
+      return any(Check(field.kind) for field in kind.fields)
+    if IsInterfaceKind(kind):
+      return any(enum.native_only for enum in kind.enums)
+    if IsArrayKind(kind):
+      return Check(kind.kind)
+    if IsMapKind(kind):
+      return Check(kind.key_kind) or Check(kind.value_kind)
+    return False
+
+  return Check(kind)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/module_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/module_unittest.py
new file mode 100644
index 00000000..2a4e852c
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/module_unittest.py
@@ -0,0 +1,31 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import sys
+import unittest
+
+from mojom.generate import module as mojom
+
+
+class ModuleTest(unittest.TestCase):
+  def testNonInterfaceAsInterfaceRequest(self):
+    """Tests that a non-interface cannot be used for interface requests."""
+    module = mojom.Module('test_module', 'test_namespace')
+    struct = mojom.Struct('TestStruct', module=module)
+    with self.assertRaises(Exception) as e:
+      mojom.InterfaceRequest(struct)
+    self.assertEquals(
+        e.exception.__str__(),
+        'Interface request requires \'x:TestStruct\' to be an interface.')
+
+  def testNonInterfaceAsAssociatedInterface(self):
+    """Tests that a non-interface type cannot be used for associated interfaces.
+    """
+    module = mojom.Module('test_module', 'test_namespace')
+    struct = mojom.Struct('TestStruct', module=module)
+    with self.assertRaises(Exception) as e:
+      mojom.AssociatedInterface(struct)
+    self.assertEquals(
+        e.exception.__str__(),
+        'Associated interface requires \'x:TestStruct\' to be an interface.')
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/pack.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/pack.py
new file mode 100644
index 00000000..61240426
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/pack.py
@@ -0,0 +1,367 @@
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import copy
+from mojom.generate import module as mojom
+
+# This module provides a mechanism for determining the packed order and offsets
+# of a mojom.Struct.
+#
+# ps = pack.PackedStruct(struct)
+# ps.packed_fields will access a list of PackedField objects, each of which
+# will have an offset, a size and a bit (for mojom.BOOLs).
+
+# Size of struct header in bytes: num_bytes [4B] + version [4B].
+HEADER_SIZE = 8
+
+
+class PackedField:
+  kind_to_size = {
+      mojom.BOOL: 1,
+      mojom.INT8: 1,
+      mojom.UINT8: 1,
+      mojom.INT16: 2,
+      mojom.UINT16: 2,
+      mojom.INT32: 4,
+      mojom.UINT32: 4,
+      mojom.FLOAT: 4,
+      mojom.HANDLE: 4,
+      mojom.MSGPIPE: 4,
+      mojom.SHAREDBUFFER: 4,
+      mojom.PLATFORMHANDLE: 4,
+      mojom.DCPIPE: 4,
+      mojom.DPPIPE: 4,
+      mojom.NULLABLE_HANDLE: 4,
+      mojom.NULLABLE_MSGPIPE: 4,
+      mojom.NULLABLE_SHAREDBUFFER: 4,
+      mojom.NULLABLE_PLATFORMHANDLE: 4,
+      mojom.NULLABLE_DCPIPE: 4,
+      mojom.NULLABLE_DPPIPE: 4,
+      mojom.INT64: 8,
+      mojom.UINT64: 8,
+      mojom.DOUBLE: 8,
+      mojom.STRING: 8,
+      mojom.NULLABLE_STRING: 8
+  }
+
+  @classmethod
+  def GetSizeForKind(cls, kind):
+    if isinstance(kind, (mojom.Array, mojom.Map, mojom.Struct, mojom.Interface,
+                         mojom.AssociatedInterface, mojom.PendingRemote,
+                         mojom.PendingAssociatedRemote)):
+      return 8
+    if isinstance(kind, mojom.Union):
+      return 16
+    if isinstance(kind, (mojom.InterfaceRequest, mojom.PendingReceiver)):
+      kind = mojom.MSGPIPE
+    if isinstance(
+        kind,
+        (mojom.AssociatedInterfaceRequest, mojom.PendingAssociatedReceiver)):
+      return 4
+    if isinstance(kind, mojom.Enum):
+      # TODO(mpcomplete): what about big enums?
+      return cls.kind_to_size[mojom.INT32]
+    if not kind in cls.kind_to_size:
+      raise Exception("Undefined type: %s. Did you forget to import the file "
+                      "containing the definition?" % kind.spec)
+    return cls.kind_to_size[kind]
+
+  @classmethod
+  def GetAlignmentForKind(cls, kind):
+    if isinstance(kind, (mojom.Interface, mojom.AssociatedInterface,
+                         mojom.PendingRemote, mojom.PendingAssociatedRemote)):
+      return 4
+    if isinstance(kind, mojom.Union):
+      return 8
+    return cls.GetSizeForKind(kind)
+
+  def __init__(self,
+               field,
+               index,
+               ordinal,
+               original_field=None,
+               sub_ordinal=None,
+               linked_value_packed_field=None):
+    """
+    Args:
+      field: the original field.
+      index: the position of the original field in the struct.
+      ordinal: the ordinal of the field for serialization.
+      original_field: See below.
+      sub_ordinal: See below.
+      linked_value_packed_field: See below.
+
+    original_field, sub_ordinal, and linked_value_packed_field are used to
+    support nullable ValueKind fields. For legacy reasons, nullable ValueKind
+    fields actually generate two PackedFields. This allows:
+
+    - backwards compatibility prior to Mojo support for nullable ValueKinds.
+    - correct packing of fields for the aforementioned backwards compatibility.
+
+    When translating Fields to PackedFields, the original field is turned into
+    two PackedFields: the first PackedField always has type mojom.BOOL, while
+    the second PackedField has the non-nullable version of the field's kind.
+
+    When constructing these PackedFields, original_field references the field
+    as defined in the mojom; the name as defined in the mojom will be used for
+    all layers above the wire/data layer.
+
+    sub_ordinal is used to sort the two PackedFields correctly with respect to
+    each other: the first mojom.BOOL field always has sub_ordinal 0, while the
+    second field always has sub_ordinal 1.
+
+    Finally, linked_value_packed_field is used by the serialization and
+    deserialization helpers, which generally just iterate over a PackedStruct's
+    PackedField's in ordinal order. This allows the helpers to easily reference
+    any related PackedFields rather than having to lookup related PackedFields
+    by index while iterating.
+    """
+    self.field = field
+    self.index = index
+    self.ordinal = ordinal
+    self.original_field = original_field
+    self.sub_ordinal = sub_ordinal
+    self.linked_value_packed_field = linked_value_packed_field
+    self.size = self.GetSizeForKind(self.field.kind)
+    self.alignment = self.GetAlignmentForKind(self.field.kind)
+    self.offset = None
+    self.bit = None
+    self.min_version = None
+
+
+def GetPad(offset, alignment):
+  """Returns the pad necessary to reserve space so that |offset + pad| equals to
+  some multiple of |alignment|."""
+  return (alignment - (offset % alignment)) % alignment
+
+
+def GetFieldOffset(field, last_field):
+  """Returns a 2-tuple of the field offset and bit (for BOOLs)."""
+  if (field.field.kind == mojom.BOOL and last_field.field.kind == mojom.BOOL
+      and last_field.bit < 7):
+    return (last_field.offset, last_field.bit + 1)
+
+  offset = last_field.offset + last_field.size
+  pad = GetPad(offset, field.alignment)
+  return (offset + pad, 0)
+
+
+def GetPayloadSizeUpToField(field):
+  """Returns the payload size (not including struct header) if |field| is the
+  last field.
+  """
+  if not field:
+    return 0
+  offset = field.offset + field.size
+  pad = GetPad(offset, 8)
+  return offset + pad
+
+
+def IsNullableValueKindPackedField(field):
+  """Returns true if `field` is derived from a nullable ValueKind field.
+
+  Nullable ValueKind fields often require special handling in the bindings due
+  to the way the implementation is constrained for wire compatibility.
+  """
+  assert isinstance(field, PackedField)
+  return field.sub_ordinal is not None
+
+
+def IsPrimaryNullableValueKindPackedField(field):
+  """Returns true if `field` is derived from a nullable ValueKind mojom field
+  and is the "primary" field.
+
+  The primary field is a bool PackedField that controls if the field should be
+  considered as present or not; it will have a reference to the PackedField that
+  holds the actual value representation if considered present.
+
+  Bindings code that translates between the wire protocol and the higher layers
+  can use this to simplify mapping multiple PackedFields to the single field
+  that is logically exposed to bindings consumers.
+  """
+  assert isinstance(field, PackedField)
+  return field.linked_value_packed_field is not None
+
+
+class PackedStruct:
+  def __init__(self, struct):
+    self.struct = struct
+    # |packed_fields| contains all the fields, in increasing offset order.
+    self.packed_fields = []
+    # |packed_fields_in_ordinal_order| refers to the same fields as
+    # |packed_fields|, but in ordinal order.
+    self.packed_fields_in_ordinal_order = []
+
+    # No fields.
+    if (len(struct.fields) == 0):
+      return
+
+    # Start by sorting by ordinal.
+    src_fields = self.packed_fields_in_ordinal_order
+    ordinal = 0
+    for index, field in enumerate(struct.fields):
+      if field.ordinal is not None:
+        ordinal = field.ordinal
+      # Nullable value types are a bit weird: they generate two PackedFields
+      # despite being a single ValueKind. This is for wire compatibility to
+      # ease the transition from legacy mojom syntax where nullable value types
+      # were not supported.
+      if isinstance(field.kind, mojom.ValueKind) and field.kind.is_nullable:
+        # The suffixes intentionally use Unicode codepoints which are considered
+        # valid C++/Java/JavaScript identifiers, yet are unlikely to be used in
+        # actual user code.
+        has_value_field = copy.copy(field)
+        has_value_field.name = f'{field.mojom_name}_$flag'
+        has_value_field.kind = mojom.BOOL
+
+        value_field = copy.copy(field)
+        value_field.name = f'{field.mojom_name}_$value'
+        value_field.kind = field.kind.MakeUnnullableKind()
+
+        value_packed_field = PackedField(value_field,
+                                         index,
+                                         ordinal,
+                                         original_field=field,
+                                         sub_ordinal=1,
+                                         linked_value_packed_field=None)
+        has_value_packed_field = PackedField(
+            has_value_field,
+            index,
+            ordinal,
+            original_field=field,
+            sub_ordinal=0,
+            linked_value_packed_field=value_packed_field)
+        src_fields.append(has_value_packed_field)
+        src_fields.append(value_packed_field)
+      else:
+        src_fields.append(PackedField(field, index, ordinal))
+      ordinal += 1
+    src_fields.sort(key=lambda field: (field.ordinal, field.sub_ordinal))
+
+    # Set |min_version| for each field.
+    next_min_version = 0
+    for packed_field in src_fields:
+      if packed_field.field.min_version is None:
+        assert next_min_version == 0
+      else:
+        assert packed_field.field.min_version >= next_min_version
+        next_min_version = packed_field.field.min_version
+      packed_field.min_version = next_min_version
+
+      if (packed_field.min_version != 0
+          and mojom.IsReferenceKind(packed_field.field.kind)
+          and not packed_field.field.kind.is_nullable):
+        raise Exception(
+            "Non-nullable reference fields are only allowed in version 0 of a "
+            "struct. %s.%s is defined with [MinVersion=%d]." %
+            (self.struct.name, packed_field.field.name,
+             packed_field.min_version))
+
+    src_field = src_fields[0]
+    src_field.offset = 0
+    src_field.bit = 0
+    dst_fields = self.packed_fields
+    dst_fields.append(src_field)
+
+    # Then find first slot that each field will fit.
+    for src_field in src_fields[1:]:
+      last_field = dst_fields[0]
+      for i in range(1, len(dst_fields)):
+        next_field = dst_fields[i]
+        offset, bit = GetFieldOffset(src_field, last_field)
+        if offset + src_field.size <= next_field.offset:
+          # Found hole.
+          src_field.offset = offset
+          src_field.bit = bit
+          dst_fields.insert(i, src_field)
+          break
+        last_field = next_field
+      if src_field.offset is None:
+        # Add to end
+        src_field.offset, src_field.bit = GetFieldOffset(src_field, last_field)
+        dst_fields.append(src_field)
+
+
+class ByteInfo:
+  def __init__(self):
+    self.is_padding = False
+    self.packed_fields = []
+
+
+def GetByteLayout(packed_struct):
+  total_payload_size = GetPayloadSizeUpToField(
+      packed_struct.packed_fields[-1] if packed_struct.packed_fields else None)
+  byte_info = [ByteInfo() for i in range(total_payload_size)]
+
+  limit_of_previous_field = 0
+  for packed_field in packed_struct.packed_fields:
+    for i in range(limit_of_previous_field, packed_field.offset):
+      byte_info[i].is_padding = True
+    byte_info[packed_field.offset].packed_fields.append(packed_field)
+    limit_of_previous_field = packed_field.offset + packed_field.size
+
+  for i in range(limit_of_previous_field, len(byte_info)):
+    byte_info[i].is_padding = True
+
+  for byte in byte_info:
+    # A given byte cannot both be padding and have a fields packed into it.
+    assert not (byte.is_padding and byte.packed_fields)
+
+  return byte_info
+
+
+class VersionInfo:
+  def __init__(self, version, num_fields, num_packed_fields, num_bytes):
+    self.version = version
+    self.num_fields = num_fields
+    self.num_packed_fields = num_packed_fields
+    self.num_bytes = num_bytes
+
+
+def GetVersionInfo(packed_struct):
+  """Get version information for a struct.
+
+  Args:
+    packed_struct: A PackedStruct instance.
+
+  Returns:
+    A non-empty list of VersionInfo instances, sorted by version in increasing
+    order.
+    Note: The version numbers may not be consecutive.
+  """
+  versions = []
+  last_version = 0
+  last_num_fields = 0
+  last_num_packed_fields = 0
+  last_payload_size = 0
+
+  for packed_field in packed_struct.packed_fields_in_ordinal_order:
+    if packed_field.min_version != last_version:
+      versions.append(
+          VersionInfo(last_version, last_num_fields, last_num_packed_fields,
+                      last_payload_size + HEADER_SIZE))
+      last_version = packed_field.min_version
+
+    # Nullable numeric fields (e.g. `int32?`) expand to two packed fields, so to
+    # avoid double-counting, only increment if the field is:
+    # - not used for representing a nullable value kind field, or
+    # - the primary field representing the nullable value kind field.
+    last_num_fields += 1 if (
+        not IsNullableValueKindPackedField(packed_field)
+        or IsPrimaryNullableValueKindPackedField(packed_field)) else 0
+
+    last_num_packed_fields += 1
+
+    # The fields are iterated in ordinal order here. However, the size of a
+    # version is determined by the last field of that version in pack order,
+    # instead of ordinal order. Therefore, we need to calculate the max value.
+    last_payload_size = max(GetPayloadSizeUpToField(packed_field),
+                            last_payload_size)
+
+  assert len(
+      versions) == 0 or last_num_packed_fields != versions[-1].num_packed_fields
+  versions.append(
+      VersionInfo(last_version, last_num_fields, last_num_packed_fields,
+                  last_payload_size + HEADER_SIZE))
+  return versions
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/pack_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/pack_unittest.py
new file mode 100644
index 00000000..7d8e4e01
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/pack_unittest.py
@@ -0,0 +1,253 @@
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import sys
+import unittest
+
+from mojom.generate import module as mojom
+from mojom.generate import pack
+
+
+class PackTest(unittest.TestCase):
+  def testOrdinalOrder(self):
+    struct = mojom.Struct('test')
+    struct.AddField('testfield1', mojom.INT32, 2)
+    struct.AddField('testfield2', mojom.INT32, 1)
+    ps = pack.PackedStruct(struct)
+
+    self.assertEqual(2, len(ps.packed_fields))
+    self.assertEqual('testfield2', ps.packed_fields[0].field.mojom_name)
+    self.assertEqual('testfield1', ps.packed_fields[1].field.mojom_name)
+
+  def testZeroFields(self):
+    struct = mojom.Struct('test')
+    ps = pack.PackedStruct(struct)
+    self.assertEqual(0, len(ps.packed_fields))
+
+  def testOneField(self):
+    struct = mojom.Struct('test')
+    struct.AddField('testfield1', mojom.INT8)
+    ps = pack.PackedStruct(struct)
+    self.assertEqual(1, len(ps.packed_fields))
+
+  def _CheckPackSequence(self, kinds, fields, offsets):
+    """Checks the pack order and offsets of a sequence of mojom.Kinds.
+
+    Args:
+      kinds: A sequence of mojom.Kinds that specify the fields that are to be
+      created.
+      fields: The expected order of the resulting fields, with the integer "1"
+      first.
+      offsets: The expected order of offsets, with the integer "0" first.
+    """
+    struct = mojom.Struct('test')
+    index = 1
+    for kind in kinds:
+      struct.AddField('%d' % index, kind)
+      index += 1
+    ps = pack.PackedStruct(struct)
+    num_fields = len(ps.packed_fields)
+    self.assertEqual(len(kinds), num_fields)
+    for i in range(num_fields):
+      self.assertEqual('%d' % fields[i], ps.packed_fields[i].field.mojom_name)
+      self.assertEqual(offsets[i], ps.packed_fields[i].offset)
+
+  def testPaddingPackedInOrder(self):
+    return self._CheckPackSequence((mojom.INT8, mojom.UINT8, mojom.INT32),
+                                   (1, 2, 3), (0, 1, 4))
+
+  def testPaddingPackedOutOfOrder(self):
+    return self._CheckPackSequence((mojom.INT8, mojom.INT32, mojom.UINT8),
+                                   (1, 3, 2), (0, 1, 4))
+
+  def testPaddingPackedOverflow(self):
+    kinds = (mojom.INT8, mojom.INT32, mojom.INT16, mojom.INT8, mojom.INT8)
+    # 2 bytes should be packed together first, followed by short, then by int.
+    fields = (1, 4, 3, 2, 5)
+    offsets = (0, 1, 2, 4, 8)
+    return self._CheckPackSequence(kinds, fields, offsets)
+
+  def testNullableTypes(self):
+    kinds = (mojom.STRING.MakeNullableKind(), mojom.HANDLE.MakeNullableKind(),
+             mojom.Struct('test_struct').MakeNullableKind(),
+             mojom.DCPIPE.MakeNullableKind(), mojom.Array().MakeNullableKind(),
+             mojom.DPPIPE.MakeNullableKind(),
+             mojom.Array(length=5).MakeNullableKind(),
+             mojom.MSGPIPE.MakeNullableKind(),
+             mojom.Interface('test_interface').MakeNullableKind(),
+             mojom.SHAREDBUFFER.MakeNullableKind(),
+             mojom.InterfaceRequest().MakeNullableKind())
+    fields = (1, 2, 4, 3, 5, 6, 8, 7, 9, 10, 11)
+    offsets = (0, 8, 12, 16, 24, 32, 36, 40, 48, 56, 60)
+    return self._CheckPackSequence(kinds, fields, offsets)
+
+  def testAllTypes(self):
+    return self._CheckPackSequence(
+        (mojom.BOOL, mojom.INT8, mojom.STRING, mojom.UINT8, mojom.INT16,
+         mojom.DOUBLE, mojom.UINT16, mojom.INT32, mojom.UINT32, mojom.INT64,
+         mojom.FLOAT, mojom.STRING, mojom.HANDLE, mojom.UINT64,
+         mojom.Struct('test'), mojom.Array(), mojom.STRING.MakeNullableKind()),
+        (1, 2, 4, 5, 7, 3, 6, 8, 9, 10, 11, 13, 12, 14, 15, 16, 17, 18),
+        (0, 1, 2, 4, 6, 8, 16, 24, 28, 32, 40, 44, 48, 56, 64, 72, 80, 88))
+
+  def testPaddingPackedOutOfOrderByOrdinal(self):
+    struct = mojom.Struct('test')
+    struct.AddField('testfield1', mojom.INT8)
+    struct.AddField('testfield3', mojom.UINT8, 3)
+    struct.AddField('testfield2', mojom.INT32, 2)
+    ps = pack.PackedStruct(struct)
+    self.assertEqual(3, len(ps.packed_fields))
+
+    # Second byte should be packed in behind first, altering order.
+    self.assertEqual('testfield1', ps.packed_fields[0].field.mojom_name)
+    self.assertEqual('testfield3', ps.packed_fields[1].field.mojom_name)
+    self.assertEqual('testfield2', ps.packed_fields[2].field.mojom_name)
+
+    # Second byte should be packed with first.
+    self.assertEqual(0, ps.packed_fields[0].offset)
+    self.assertEqual(1, ps.packed_fields[1].offset)
+    self.assertEqual(4, ps.packed_fields[2].offset)
+
+  def testBools(self):
+    struct = mojom.Struct('test')
+    struct.AddField('bit0', mojom.BOOL)
+    struct.AddField('bit1', mojom.BOOL)
+    struct.AddField('int', mojom.INT32)
+    struct.AddField('bit2', mojom.BOOL)
+    struct.AddField('bit3', mojom.BOOL)
+    struct.AddField('bit4', mojom.BOOL)
+    struct.AddField('bit5', mojom.BOOL)
+    struct.AddField('bit6', mojom.BOOL)
+    struct.AddField('bit7', mojom.BOOL)
+    struct.AddField('bit8', mojom.BOOL)
+    ps = pack.PackedStruct(struct)
+    self.assertEqual(10, len(ps.packed_fields))
+
+    # First 8 bits packed together.
+    for i in range(8):
+      pf = ps.packed_fields[i]
+      self.assertEqual(0, pf.offset)
+      self.assertEqual("bit%d" % i, pf.field.mojom_name)
+      self.assertEqual(i, pf.bit)
+
+    # Ninth bit goes into second byte.
+    self.assertEqual("bit8", ps.packed_fields[8].field.mojom_name)
+    self.assertEqual(1, ps.packed_fields[8].offset)
+    self.assertEqual(0, ps.packed_fields[8].bit)
+
+    # int comes last.
+    self.assertEqual("int", ps.packed_fields[9].field.mojom_name)
+    self.assertEqual(4, ps.packed_fields[9].offset)
+
+  def testMinVersion(self):
+    """Tests that |min_version| is properly set for packed fields."""
+    struct = mojom.Struct('test')
+    struct.AddField('field_2', mojom.BOOL, 2)
+    struct.AddField('field_0', mojom.INT32, 0)
+    struct.AddField('field_1', mojom.INT64, 1)
+    ps = pack.PackedStruct(struct)
+
+    self.assertEqual('field_0', ps.packed_fields[0].field.mojom_name)
+    self.assertEqual('field_2', ps.packed_fields[1].field.mojom_name)
+    self.assertEqual('field_1', ps.packed_fields[2].field.mojom_name)
+
+    self.assertEqual(0, ps.packed_fields[0].min_version)
+    self.assertEqual(0, ps.packed_fields[1].min_version)
+    self.assertEqual(0, ps.packed_fields[2].min_version)
+
+    struct.fields[0].attributes = {'MinVersion': 1}
+    ps = pack.PackedStruct(struct)
+
+    self.assertEqual(0, ps.packed_fields[0].min_version)
+    self.assertEqual(1, ps.packed_fields[1].min_version)
+    self.assertEqual(0, ps.packed_fields[2].min_version)
+
+  def testGetVersionInfoEmptyStruct(self):
+    """Tests that pack.GetVersionInfo() never returns an empty list, even for
+    empty structs.
+    """
+    struct = mojom.Struct('test')
+    ps = pack.PackedStruct(struct)
+
+    versions = pack.GetVersionInfo(ps)
+    self.assertEqual(1, len(versions))
+    self.assertEqual(0, versions[0].version)
+    self.assertEqual(0, versions[0].num_fields)
+    self.assertEqual(8, versions[0].num_bytes)
+
+  def testGetVersionInfoComplexOrder(self):
+    """Tests pack.GetVersionInfo() using a struct whose definition order,
+    ordinal order and pack order for fields are all different.
+    """
+    struct = mojom.Struct('test')
+    struct.AddField(
+        'field_3', mojom.BOOL, ordinal=3, attributes={'MinVersion': 3})
+    struct.AddField('field_0', mojom.INT32, ordinal=0)
+    struct.AddField(
+        'field_1', mojom.INT64, ordinal=1, attributes={'MinVersion': 2})
+    struct.AddField(
+        'field_2', mojom.INT64, ordinal=2, attributes={'MinVersion': 3})
+    ps = pack.PackedStruct(struct)
+
+    versions = pack.GetVersionInfo(ps)
+    self.assertEqual(3, len(versions))
+
+    self.assertEqual(0, versions[0].version)
+    self.assertEqual(1, versions[0].num_fields)
+    self.assertEqual(16, versions[0].num_bytes)
+
+    self.assertEqual(2, versions[1].version)
+    self.assertEqual(2, versions[1].num_fields)
+    self.assertEqual(24, versions[1].num_bytes)
+
+    self.assertEqual(3, versions[2].version)
+    self.assertEqual(4, versions[2].num_fields)
+    self.assertEqual(32, versions[2].num_bytes)
+
+  def testGetVersionInfoPackedStruct(self):
+    """Tests that pack.GetVersionInfo() correctly sets version, num_fields,
+    and num_packed_fields for a packed struct.
+    """
+    struct = mojom.Struct('test')
+    struct.AddField('field_0', mojom.BOOL, ordinal=0)
+    struct.AddField('field_1',
+                    mojom.NULLABLE_BOOL,
+                    ordinal=1,
+                    attributes={'MinVersion': 1})
+    struct.AddField('field_2',
+                    mojom.NULLABLE_BOOL,
+                    ordinal=2,
+                    attributes={'MinVersion': 2})
+    ps = pack.PackedStruct(struct)
+    versions = pack.GetVersionInfo(ps)
+
+    self.assertEqual(3, len(versions))
+    self.assertEqual(0, versions[0].version)
+    self.assertEqual(1, versions[1].version)
+    self.assertEqual(2, versions[2].version)
+    self.assertEqual(1, versions[0].num_fields)
+    self.assertEqual(2, versions[1].num_fields)
+    self.assertEqual(3, versions[2].num_fields)
+    self.assertEqual(1, versions[0].num_packed_fields)
+    self.assertEqual(3, versions[1].num_packed_fields)
+    self.assertEqual(5, versions[2].num_packed_fields)
+
+  def testInterfaceAlignment(self):
+    """Tests that interfaces are aligned on 4-byte boundaries, although the size
+    of an interface is 8 bytes.
+    """
+    kinds = (mojom.INT32, mojom.Interface('test_interface'))
+    fields = (1, 2)
+    offsets = (0, 4)
+    self._CheckPackSequence(kinds, fields, offsets)
+
+  def testAssociatedInterfaceAlignment(self):
+    """Tests that associated interfaces are aligned on 4-byte boundaries,
+    although the size of an associated interface is 8 bytes.
+    """
+    kinds = (mojom.INT32,
+             mojom.AssociatedInterface(mojom.Interface('test_interface')))
+    fields = (1, 2)
+    offsets = (0, 4)
+    self._CheckPackSequence(kinds, fields, offsets)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/template_expander.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/template_expander.py
new file mode 100644
index 00000000..807e2a4f
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/template_expander.py
@@ -0,0 +1,82 @@
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Based on third_party/WebKit/Source/build/scripts/template_expander.py.
+
+import os.path
+import sys
+
+from mojom import fileutil
+
+fileutil.AddLocalRepoThirdPartyDirToModulePath()
+import jinja2
+
+
+def ApplyTemplate(mojo_generator, path_to_template, params, **kwargs):
+  loader = jinja2.ModuleLoader(
+      os.path.join(mojo_generator.bytecode_path,
+                   "%s.zip" % mojo_generator.GetTemplatePrefix()))
+  final_kwargs = dict(mojo_generator.GetJinjaParameters())
+  final_kwargs.update(kwargs)
+
+  jinja_env = jinja2.Environment(
+      loader=loader, keep_trailing_newline=True, **final_kwargs)
+  jinja_env.globals.update(mojo_generator.GetGlobals())
+  jinja_env.filters.update(mojo_generator.GetFilters())
+  template = jinja_env.get_template(path_to_template)
+  return template.render(params)
+
+
+def UseJinja(path_to_template, **kwargs):
+  def RealDecorator(generator):
+    def GeneratorInternal(*args, **kwargs2):
+      parameters = generator(*args, **kwargs2)
+      return ApplyTemplate(args[0], path_to_template, parameters, **kwargs)
+
+    GeneratorInternal.__name__ = generator.__name__
+    return GeneratorInternal
+
+  return RealDecorator
+
+
+def ApplyImportedTemplate(mojo_generator, path_to_template, filename, params,
+                          **kwargs):
+  loader = jinja2.FileSystemLoader(searchpath=path_to_template)
+  final_kwargs = dict(mojo_generator.GetJinjaParameters())
+  final_kwargs.update(kwargs)
+
+  jinja_env = jinja2.Environment(
+      loader=loader, keep_trailing_newline=True, **final_kwargs)
+  jinja_env.globals.update(mojo_generator.GetGlobals())
+  jinja_env.filters.update(mojo_generator.GetFilters())
+  template = jinja_env.get_template(filename)
+  return template.render(params)
+
+
+def UseJinjaForImportedTemplate(func):
+  def wrapper(*args, **kwargs):
+    parameters = func(*args, **kwargs)
+    path_to_template = args[1]
+    filename = args[2]
+    return ApplyImportedTemplate(args[0], path_to_template, filename,
+                                 parameters)
+
+  wrapper.__name__ = func.__name__
+  return wrapper
+
+
+def PrecompileTemplates(generator_modules, output_dir):
+  for module in generator_modules.values():
+    generator = module.Generator(None)
+    jinja_env = jinja2.Environment(
+        loader=jinja2.FileSystemLoader([
+            os.path.join(
+                os.path.dirname(module.__file__), generator.GetTemplatePrefix())
+        ]))
+    jinja_env.filters.update(generator.GetFilters())
+    jinja_env.compile_templates(os.path.join(
+        output_dir, "%s.zip" % generator.GetTemplatePrefix()),
+                                extensions=["tmpl"],
+                                zip="stored",
+                                ignore_errors=False)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/translate.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/translate.py
new file mode 100644
index 00000000..83bb297f
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/translate.py
@@ -0,0 +1,1258 @@
+# Copyright 2013 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Convert parse tree to AST.
+
+This module converts the parse tree to the AST we use for code generation. The
+main entry point is OrderedModule, which gets passed the parser
+representation of a mojom file. When called it's assumed that all imports have
+already been parsed and converted to ASTs before.
+"""
+
+import itertools
+import os
+import re
+
+from collections import OrderedDict
+from mojom.generate import generator
+from mojom.generate import module as mojom
+from mojom.parse import ast
+
+
+is_running_backwards_compatibility_check_hack = False
+
+### DO NOT ADD ENTRIES TO THIS LIST. ###
+_EXTENSIBLE_ENUMS_MISSING_DEFAULT = (
+    'x:arc.keymaster.mojom.Algorithm',
+    'x:arc.keymaster.mojom.Digest',
+    'x:arc.keymaster.mojom.SignatureResult',
+    'x:arc.mojom.AccessibilityActionType',
+    'x:arc.mojom.AccessibilityBooleanProperty',
+    'x:arc.mojom.AccessibilityEventIntListProperty',
+    'x:arc.mojom.AccessibilityEventIntProperty',
+    'x:arc.mojom.AccessibilityEventStringProperty',
+    'x:arc.mojom.AccessibilityEventType',
+    'x:arc.mojom.AccessibilityFilterType',
+    'x:arc.mojom.AccessibilityIntListProperty',
+    'x:arc.mojom.AccessibilityIntProperty',
+    'x:arc.mojom.AccessibilityLiveRegionType',
+    'x:arc.mojom.AccessibilityNotificationStateType',
+    'x:arc.mojom.AccessibilityRangeType',
+    'x:arc.mojom.AccessibilitySelectionMode',
+    'x:arc.mojom.AccessibilityStringListProperty',
+    'x:arc.mojom.AccessibilityStringProperty',
+    'x:arc.mojom.AccessibilityWindowBooleanProperty',
+    'x:arc.mojom.AccessibilityWindowIntListProperty',
+    'x:arc.mojom.AccessibilityWindowIntProperty',
+    'x:arc.mojom.AccessibilityWindowStringProperty',
+    'x:arc.mojom.AccessibilityWindowType',
+    'x:arc.mojom.AccountCheckStatus',
+    'x:arc.mojom.AccountUpdateType',
+    'x:arc.mojom.ActionType',
+    'x:arc.mojom.Algorithm',
+    'x:arc.mojom.AndroidIdSource',
+    'x:arc.mojom.AnrSource',
+    'x:arc.mojom.AnrType',
+    'x:arc.mojom.AppDiscoveryRequestState',
+    'x:arc.mojom.AppKillType',
+    'x:arc.mojom.AppPermission',
+    'x:arc.mojom.AppPermissionGroup',
+    'x:arc.mojom.AppReinstallState',
+    'x:arc.mojom.AppShortcutItemType',
+    'x:arc.mojom.ArcAuthCodeStatus',
+    'x:arc.mojom.ArcClipboardDragDropEvent',
+    'x:arc.mojom.ArcCorePriAbiMigEvent',
+    'x:arc.mojom.ArcDnsQuery',
+    'x:arc.mojom.ArcImageCopyPasteCompatAction',
+    'x:arc.mojom.ArcNetworkError',
+    'x:arc.mojom.ArcNetworkEvent',
+    'x:arc.mojom.ArcNotificationEvent',
+    'x:arc.mojom.ArcNotificationExpandState',
+    'x:arc.mojom.ArcNotificationPriority',
+    'x:arc.mojom.ArcNotificationRemoteInputState',
+    'x:arc.mojom.ArcNotificationShownContents',
+    'x:arc.mojom.ArcNotificationStyle',
+    'x:arc.mojom.ArcNotificationType',
+    'x:arc.mojom.ArcPipEvent',
+    'x:arc.mojom.ArcResizeLockState',
+    'x:arc.mojom.ArcSignInSuccess',
+    'x:arc.mojom.ArcTimerResult',
+    'x:arc.mojom.AudioSwitch',
+    'x:arc.mojom.BluetoothAclState',
+    'x:arc.mojom.BluetoothAdapterState',
+    'x:arc.mojom.BluetoothAdvertisingDataType',
+    'x:arc.mojom.BluetoothBondState',
+    'x:arc.mojom.BluetoothDeviceType',
+    'x:arc.mojom.BluetoothDiscoveryState',
+    'x:arc.mojom.BluetoothGattDBAttributeType',
+    'x:arc.mojom.BluetoothGattStatus',
+    'x:arc.mojom.BluetoothPropertyType',
+    'x:arc.mojom.BluetoothScanMode',
+    'x:arc.mojom.BluetoothSdpAttributeType',
+    'x:arc.mojom.BluetoothSocketType',
+    'x:arc.mojom.BluetoothStatus',
+    'x:arc.mojom.BootType',
+    'x:arc.mojom.CaptionTextShadowType',
+    'x:arc.mojom.ChangeType',
+    'x:arc.mojom.ChromeAccountType',
+    'x:arc.mojom.ChromeApp',
+    'x:arc.mojom.ChromePage',
+    'x:arc.mojom.ClockId',
+    'x:arc.mojom.CloudProvisionFlowError',
+    'x:arc.mojom.CommandResultType',
+    'x:arc.mojom.CompanionLibApiId',
+    'x:arc.mojom.ConnectionStateType',
+    'x:arc.mojom.ContentChangeType',
+    'x:arc.mojom.CpuRestrictionState',
+    'x:arc.mojom.CursorCoordinateSpace',
+    'x:arc.mojom.DataRestoreStatus',
+    'x:arc.mojom.DecoderStatus',
+    'x:arc.mojom.DeviceType',
+    'x:arc.mojom.Digest',
+    'x:arc.mojom.DisplayWakeLockType',
+    'x:arc.mojom.EapMethod',
+    'x:arc.mojom.EapPhase2Method',
+    'x:arc.mojom.FileSelectorEventType',
+    'x:arc.mojom.GMSCheckInError',
+    'x:arc.mojom.GMSSignInError',
+    'x:arc.mojom.GeneralSignInError',
+    'x:arc.mojom.GetNetworksRequestType',
+    'x:arc.mojom.HalPixelFormat',
+    'x:arc.mojom.IPAddressType',
+    'x:arc.mojom.InstallErrorReason',
+    'x:arc.mojom.KeyFormat',
+    'x:arc.mojom.KeyManagement',
+    'x:arc.mojom.KeyPurpose',
+    'x:arc.mojom.KeymasterError',
+    'x:arc.mojom.MainAccountHashMigrationStatus',
+    'x:arc.mojom.MainAccountResolutionStatus',
+    'x:arc.mojom.ManagementChangeStatus',
+    'x:arc.mojom.ManagementState',
+    'x:arc.mojom.MessageCenterVisibility',
+    'x:arc.mojom.MetricsType',
+    'x:arc.mojom.MountEvent',
+    'x:arc.mojom.NativeBridgeType',
+    'x:arc.mojom.NetworkResult',
+    'x:arc.mojom.NetworkType',
+    'x:arc.mojom.OemCryptoAlgorithm',
+    'x:arc.mojom.OemCryptoCipherMode',
+    'x:arc.mojom.OemCryptoHdcpCapability',
+    'x:arc.mojom.OemCryptoLicenseType',
+    'x:arc.mojom.OemCryptoPrivateKey',
+    'x:arc.mojom.OemCryptoProvisioningMethod',
+    'x:arc.mojom.OemCryptoResult',
+    'x:arc.mojom.OemCryptoRsaPaddingScheme',
+    'x:arc.mojom.OemCryptoUsageEntryStatus',
+    'x:arc.mojom.Padding',
+    'x:arc.mojom.PaiFlowState',
+    'x:arc.mojom.PatternType',
+    'x:arc.mojom.PressureLevel',
+    'x:arc.mojom.PrintColorMode',
+    'x:arc.mojom.PrintContentType',
+    'x:arc.mojom.PrintDuplexMode',
+    'x:arc.mojom.PrinterStatus',
+    'x:arc.mojom.ProcessState',
+    'x:arc.mojom.PurchaseState',
+    'x:arc.mojom.ReauthReason',
+    'x:arc.mojom.ScaleFactor',
+    'x:arc.mojom.SecurityType',
+    'x:arc.mojom.SegmentStyle',
+    'x:arc.mojom.SelectFilesActionType',
+    'x:arc.mojom.SetNativeChromeVoxResponse',
+    'x:arc.mojom.ShowPackageInfoPage',
+    'x:arc.mojom.SpanType',
+    'x:arc.mojom.SupportedLinkChangeSource',
+    'x:arc.mojom.TetheringClientState',
+    'x:arc.mojom.TextInputType',
+    'x:arc.mojom.TtsEventType',
+    'x:arc.mojom.VideoCodecProfile',
+    'x:arc.mojom.VideoDecodeAccelerator.Result',
+    'x:arc.mojom.VideoEncodeAccelerator.Error',
+    'x:arc.mojom.VideoFrameStorageType',
+    'x:arc.mojom.VideoPixelFormat',
+    'x:arc.mojom.WakefulnessMode',
+    'x:arc.mojom.WebApkInstallResult',
+    'x:ash.ime.mojom.InputFieldType',
+    'x:ash.ime.mojom.PersonalizationMode',
+    'x:ash.language.mojom.FeatureId',
+    'x:blink.mojom.ScrollRestorationType',
+    'x:chromeos.cdm.mojom.CdmKeyStatus',
+    'x:chromeos.cdm.mojom.CdmMessageType',
+    'x:chromeos.cdm.mojom.CdmSessionType',
+    'x:chromeos.cdm.mojom.DecryptStatus',
+    'x:chromeos.cdm.mojom.EmeInitDataType',
+    'x:chromeos.cdm.mojom.EncryptionScheme',
+    'x:chromeos.cdm.mojom.HdcpVersion',
+    'x:chromeos.cdm.mojom.OutputProtection.LinkType',
+    'x:chromeos.cdm.mojom.OutputProtection.ProtectionType',
+    'x:chromeos.cdm.mojom.PromiseException',
+    'x:chromeos.cfm.mojom.EnqueuePriority',
+    'x:chromeos.cfm.mojom.LoggerErrorCode',
+    'x:chromeos.cfm.mojom.LoggerState',
+    'x:chromeos.cros_healthd.mojom.CryptoAlgorithm',
+    'x:chromeos.cros_healthd.mojom.EncryptionState',
+    'x:chromeos.machine_learning.mojom.AnnotationUsecase',
+    'x:chromeos.machine_learning.mojom.BuiltinModelId',
+    'x:chromeos.machine_learning.mojom.CreateGraphExecutorResult',
+    'x:chromeos.machine_learning.mojom.DocumentScannerResultStatus',
+    'x:chromeos.machine_learning.mojom.EndpointReason',
+    'x:chromeos.machine_learning.mojom.EndpointerType',
+    'x:chromeos.machine_learning.mojom.ExecuteResult',
+    'x:chromeos.machine_learning.mojom.GrammarCheckerResult.Status',
+    'x:chromeos.machine_learning.mojom.HandwritingRecognizerResult.Status',
+    'x:chromeos.machine_learning.mojom.LoadHandwritingModelResult',
+    'x:chromeos.machine_learning.mojom.LoadModelResult',
+    'x:chromeos.machine_learning.mojom.Rotation',
+    'x:chromeos.network_config.mojom.ConnectionStateType',
+    'x:chromeos.network_config.mojom.DeviceStateType',
+    'x:chromeos.network_config.mojom.IPConfigType',
+    'x:chromeos.network_config.mojom.NetworkType',
+    'x:chromeos.network_config.mojom.OncSource',
+    'x:chromeos.network_config.mojom.PolicySource',
+    'x:chromeos.network_config.mojom.PortalState',
+    'x:chromeos.wilco_dtc_supportd.mojom.WilcoDtcSupportdEvent',
+    'x:chromeos.wilco_dtc_supportd.mojom.WilcoDtcSupportdWebRequestHttpMethod',
+    'x:chromeos.wilco_dtc_supportd.mojom.WilcoDtcSupportdWebRequestStatus',
+    'x:cros.mojom.CameraClientType',
+    'x:cros.mojom.CameraMetadataSectionStart',
+    'x:cros.mojom.CameraMetadataTag',
+    'x:cros.mojom.HalPixelFormat',
+    'x:crosapi.mojom.AllowedPaths',
+    'x:crosapi.mojom.BrowserAppInstanceType',
+    'x:crosapi.mojom.CreationResult',
+    'x:crosapi.mojom.DeviceAccessResultCode',
+    'x:crosapi.mojom.DeviceMode',
+    'x:crosapi.mojom.DlpRestrictionLevel',
+    'x:crosapi.mojom.ExoImeSupport',
+    'x:crosapi.mojom.FullscreenVisibility',
+    'x:crosapi.mojom.GoogleServiceAuthError.State',
+    'x:crosapi.mojom.IsInstallableResult',
+    'x:crosapi.mojom.KeyTag',
+    'x:crosapi.mojom.KeystoreSigningAlgorithmName',
+    'x:crosapi.mojom.KeystoreType',
+    'x:crosapi.mojom.LacrosFeedbackSource',
+    'x:crosapi.mojom.MemoryPressureLevel',
+    'x:crosapi.mojom.MetricsReportingManaged',
+    'x:crosapi.mojom.NotificationType',
+    'x:crosapi.mojom.OndeviceHandwritingSupport',
+    'x:crosapi.mojom.OpenResult',
+    'x:crosapi.mojom.PolicyDomain',
+    'x:crosapi.mojom.RegistrationCodeType',
+    'x:crosapi.mojom.ScaleFactor',
+    'x:crosapi.mojom.SearchResult.OptionalBool',
+    'x:crosapi.mojom.SelectFileDialogType',
+    'x:crosapi.mojom.SelectFileResult',
+    'x:crosapi.mojom.SharesheetResult',
+    'x:crosapi.mojom.TouchEventType',
+    'x:crosapi.mojom.VideoRotation',
+    'x:crosapi.mojom.WallpaperLayout',
+    'x:crosapi.mojom.WebAppInstallResultCode',
+    'x:crosapi.mojom.WebAppUninstallResultCode',
+    'x:device.mojom.HidBusType',
+    'x:device.mojom.WakeLockReason',
+    'x:device.mojom.WakeLockType',
+    'x:drivefs.mojom.DialogReason.Type',
+    'x:drivefs.mojom.DriveError.Type',
+    'x:drivefs.mojom.DriveFsDelegate.ExtensionConnectionStatus',
+    'x:drivefs.mojom.FileMetadata.CanPinStatus',
+    'x:drivefs.mojom.FileMetadata.Type',
+    'x:drivefs.mojom.ItemEventReason',
+    'x:drivefs.mojom.MirrorPathStatus',
+    'x:drivefs.mojom.MirrorSyncStatus',
+    'x:drivefs.mojom.QueryParameters.SortField',
+    'x:fuzz.mojom.FuzzEnum',
+    'x:media.mojom.FillLightMode',
+    'x:media.mojom.MeteringMode',
+    'x:media.mojom.PowerLineFrequency',
+    'x:media.mojom.RedEyeReduction',
+    'x:media.mojom.ResolutionChangePolicy',
+    'x:media.mojom.VideoCaptureApi',
+    'x:media.mojom.VideoCaptureBufferType',
+    'x:media.mojom.VideoCaptureError',
+    'x:media.mojom.VideoCaptureFrameDropReason',
+    'x:media.mojom.VideoCapturePixelFormat',
+    'x:media.mojom.VideoCaptureTransportType',
+    'x:media.mojom.VideoFacingMode',
+    'x:media_session.mojom.AudioFocusType',
+    'x:media_session.mojom.CameraState',
+    'x:media_session.mojom.EnforcementMode',
+    'x:media_session.mojom.MediaAudioVideoState',
+    'x:media_session.mojom.MediaImageBitmapColorType',
+    'x:media_session.mojom.MediaPictureInPictureState',
+    'x:media_session.mojom.MediaPlaybackState',
+    'x:media_session.mojom.MediaSession.SuspendType',
+    'x:media_session.mojom.MediaSessionAction',
+    'x:media_session.mojom.MediaSessionImageType',
+    'x:media_session.mojom.MediaSessionInfo.SessionState',
+    'x:media_session.mojom.MicrophoneState',
+    'x:ml.model_loader.mojom.ComputeResult',
+    'x:ml.model_loader.mojom.CreateModelLoaderResult',
+    'x:ml.model_loader.mojom.LoadModelResult',
+    'x:mojo.test.AnExtensibleEnum',
+    'x:mojo.test.EnumB',
+    'x:mojo.test.ExtensibleEmptyEnum',
+    'x:mojo.test.enum_default_unittest.mojom.ExtensibleEnumWithoutDefault',
+    'x:network.mojom.WebSandboxFlags',
+    'x:payments.mojom.BillingResponseCode',
+    'x:payments.mojom.CreateDigitalGoodsResponseCode',
+    'x:payments.mojom.ItemType',
+    'x:printing.mojom.PrinterType',
+    'x:ui.mojom.KeyboardCode',
+)
+### DO NOT ADD ENTRIES TO THIS LIST. ###
+
+
+def _DuplicateName(values):
+  """Returns the 'mojom_name' of the first entry in |values| whose 'mojom_name'
+  has already been encountered. If there are no duplicates, returns None."""
+  names = set()
+  for value in values:
+    if value.mojom_name in names:
+      return value.mojom_name
+    names.add(value.mojom_name)
+  return None
+
+
+def _ElemsOfType(elems, elem_type, scope):
+  """Find all elements of the given type.
+
+  Args:
+    elems: {Sequence[Any]} Sequence of elems.
+    elem_type: {Type[C]} Extract all elems of this type.
+    scope: {str} The name of the surrounding scope (e.g. struct
+        definition). Used in error messages.
+
+  Returns:
+    {List[C]} All elems of matching type.
+  """
+  assert isinstance(elem_type, type)
+  result = [elem for elem in elems if isinstance(elem, elem_type)]
+  duplicate_name = _DuplicateName(result)
+  if duplicate_name:
+    raise Exception('Names in mojom must be unique within a scope. The name '
+                    '"%s" is used more than once within the scope "%s".' %
+                    (duplicate_name, scope))
+  return result
+
+
+def _ProcessElements(scope, elements, operations_by_type):
+  """Iterates over the given elements, running a function from
+  operations_by_type for any element that matches a key in that dict. The scope
+  is the name of the surrounding scope, such as a filename or struct name, used
+  only in error messages."""
+  names_in_this_scope = set()
+  for element in elements:
+    # pylint: disable=unidiomatic-typecheck
+    element_type = type(element)
+    if element_type in operations_by_type:
+      if element.mojom_name in names_in_this_scope:
+        raise Exception('Names must be unique within a scope. The name "%s" is '
+                        'used more than once within the scope "%s".' %
+                        (duplicate_name, scope))
+      operations_by_type[element_type](element)
+
+
+def _MapKind(kind):
+  map_to_kind = {
+      'bool': 'b',
+      'int8': 'i8',
+      'int16': 'i16',
+      'int32': 'i32',
+      'int64': 'i64',
+      'uint8': 'u8',
+      'uint16': 'u16',
+      'uint32': 'u32',
+      'uint64': 'u64',
+      'float': 'f',
+      'double': 'd',
+      'string': 's',
+      'handle': 'h',
+      'handle<data_pipe_consumer>': 'h:d:c',
+      'handle<data_pipe_producer>': 'h:d:p',
+      'handle<message_pipe>': 'h:m',
+      'handle<shared_buffer>': 'h:s',
+      'handle<platform>': 'h:p'
+  }
+  if kind.endswith('?'):
+    base_kind = _MapKind(kind[0:-1])
+    return '?' + base_kind
+  if kind.endswith('}'):
+    lbracket = kind.rfind('{')
+    value = kind[0:lbracket]
+    return 'm[' + _MapKind(kind[lbracket + 1:-1]) + '][' + _MapKind(value) + ']'
+  if kind.endswith(']'):
+    lbracket = kind.rfind('[')
+    typename = kind[0:lbracket]
+    return 'a' + kind[lbracket + 1:-1] + ':' + _MapKind(typename)
+  if kind.startswith('asso<'):
+    assert kind.endswith('>')
+    return 'asso:' + _MapKind(kind[5:-1])
+  if kind.startswith('rmt<'):
+    assert kind.endswith('>')
+    return 'rmt:' + _MapKind(kind[4:-1])
+  if kind.startswith('rcv<'):
+    assert kind.endswith('>')
+    return 'rcv:' + _MapKind(kind[4:-1])
+  if kind.startswith('rma<'):
+    assert kind.endswith('>')
+    return 'rma:' + _MapKind(kind[4:-1])
+  if kind.startswith('rca<'):
+    assert kind.endswith('>')
+    return 'rca:' + _MapKind(kind[4:-1])
+  if kind in map_to_kind:
+    return map_to_kind[kind]
+  return 'x:' + kind
+
+
+def _MapAttributeValue(module, kind, value):
+  # True/False/None
+  if value is None:
+    return value
+  if not isinstance(value, str):
+    return value
+  # Is the attribute value the name of a feature?
+  try:
+    # Features cannot be nested in other types, so lookup in the global scope.
+    trial = _LookupKind(module.kinds, 'x:' + value,
+                        _GetScopeForKind(module, kind))
+    if isinstance(trial, mojom.Feature):
+      return trial
+  except ValueError:
+    pass
+  # Is the attribute value a constant or enum value?
+  try:
+    trial = _LookupValue(module, None, None, ('IDENTIFIER', value))
+    if isinstance(trial, mojom.ConstantValue):
+      return trial.constant
+    if isinstance(trial, mojom.EnumValue):
+      return trial
+  except ValueError:
+    pass
+  # If not a referenceable mojo type - return as a string.
+  return value
+
+
+def _AttributeListToDict(module, kind, attribute_list):
+  if attribute_list is None:
+    return None
+  assert isinstance(attribute_list, ast.AttributeList)
+  attributes = dict()
+  for attribute in attribute_list:
+    if attribute.key in attributes:
+      raise Exception("Duplicate key (%s) in attribute list" % attribute.key)
+    attributes[attribute.key] = _MapAttributeValue(module, kind,
+                                                   attribute.value)
+  return attributes
+
+
+builtin_values = frozenset([
+    "double.INFINITY", "double.NEGATIVE_INFINITY", "double.NAN",
+    "float.INFINITY", "float.NEGATIVE_INFINITY", "float.NAN"
+])
+
+
+def _IsBuiltinValue(value):
+  return value in builtin_values
+
+
+def _LookupKind(kinds, spec, scope):
+  """Tries to find which Kind a spec refers to, given the scope in which its
+  referenced. Starts checking from the narrowest scope to most general. For
+  example, given a struct field like
+    Foo.Bar x;
+  Foo.Bar could refer to the type 'Bar' in the 'Foo' namespace, or an inner
+  type 'Bar' in the struct 'Foo' in the current namespace.
+
+  |scope| is a tuple that looks like (namespace, struct/interface), referring
+  to the location where the type is referenced."""
+  if spec.startswith('x:'):
+    mojom_name = spec[2:]
+    for i in range(len(scope), -1, -1):
+      test_spec = 'x:'
+      if i > 0:
+        test_spec += '.'.join(scope[:i]) + '.'
+      test_spec += mojom_name
+      kind = kinds.get(test_spec)
+      if kind:
+        return kind
+
+  return kinds.get(spec)
+
+
+def _GetScopeForKind(module, kind):
+  """For a given kind, returns a tuple of progressively more specific names
+  used to qualify the kind. For example if kind is an enum named Bar nested in a
+  struct Foo within module 'foo', this would return ('foo', 'Foo', 'Bar')"""
+  if isinstance(kind, mojom.Enum) and kind.parent_kind:
+    # Enums may be nested in other kinds.
+    return _GetScopeForKind(module, kind.parent_kind) + (kind.mojom_name, )
+
+  module_fragment = (module.mojom_namespace, ) if module.mojom_namespace else ()
+  kind_fragment = (kind.mojom_name, ) if kind else ()
+  return module_fragment + kind_fragment
+
+
+def _LookupValueInScope(module, kind, identifier):
+  """Given a kind and an identifier, this attempts to resolve the given
+  identifier to a concrete NamedValue within the scope of the given kind."""
+  scope = _GetScopeForKind(module, kind)
+  for i in reversed(range(len(scope) + 1)):
+    qualified_name = '.'.join(scope[:i] + (identifier, ))
+    value = module.values.get(qualified_name)
+    if value:
+      return value
+  return None
+
+
+def _LookupValue(module, parent_kind, implied_kind, ast_leaf_node):
+  """Resolves a leaf node in the form ('IDENTIFIER', 'x') to a constant value
+  identified by 'x' in some mojom definition. parent_kind is used as context
+  when resolving the identifier. If the given leaf node is not an IDENTIFIER
+  (e.g. already a constant value), it is returned as-is.
+
+  If implied_kind is provided, the parsed identifier may also be resolved within
+  its scope as fallback. This can be useful for more concise value references
+  when assigning enum-typed constants or field values."""
+  if not isinstance(ast_leaf_node, tuple) or ast_leaf_node[0] != 'IDENTIFIER':
+    return ast_leaf_node
+
+  # First look for a known user-defined identifier to resolve this within the
+  # enclosing scope.
+  identifier = ast_leaf_node[1]
+
+  value = _LookupValueInScope(module, parent_kind, identifier)
+  if value:
+    return value
+
+  # Next look in the scope of implied_kind, if provided.
+  value = (implied_kind and implied_kind.module and _LookupValueInScope(
+      implied_kind.module, implied_kind, identifier))
+  if value:
+    return value
+
+  # Fall back on defined builtin symbols
+  if _IsBuiltinValue(identifier):
+    return mojom.BuiltinValue(identifier)
+
+  raise ValueError('Unknown identifier %s' % identifier)
+
+
+def _Kind(kinds, spec, scope):
+  """Convert a type name into a mojom.Kind object.
+
+  As a side-effect this function adds the result to 'kinds'.
+
+  Args:
+    kinds: {Dict[str, mojom.Kind]} All known kinds up to this point, indexed by
+        their names.
+    spec: {str} A name uniquely identifying a type.
+    scope: {Tuple[str, str]} A tuple that looks like (namespace,
+        struct/interface), referring to the location where the type is
+        referenced.
+
+  Returns:
+    {mojom.Kind} The type corresponding to 'spec'.
+  """
+  kind = _LookupKind(kinds, spec, scope)
+  if kind:
+    return kind
+
+  if spec.startswith('?'):
+    kind = _Kind(kinds, spec[1:], scope)
+    kind = kind.MakeNullableKind()
+  elif spec.startswith('a:'):
+    kind = mojom.Array(_Kind(kinds, spec[2:], scope))
+  elif spec.startswith('asso:'):
+    inner_kind = _Kind(kinds, spec[5:], scope)
+    if isinstance(inner_kind, mojom.InterfaceRequest):
+      kind = mojom.AssociatedInterfaceRequest(inner_kind)
+    else:
+      kind = mojom.AssociatedInterface(inner_kind)
+  elif spec.startswith('a'):
+    colon = spec.find(':')
+    length = int(spec[1:colon])
+    kind = mojom.Array(_Kind(kinds, spec[colon + 1:], scope), length)
+  elif spec.startswith('r:'):
+    kind = mojom.InterfaceRequest(_Kind(kinds, spec[2:], scope))
+  elif spec.startswith('rmt:'):
+    kind = mojom.PendingRemote(_Kind(kinds, spec[4:], scope))
+  elif spec.startswith('rcv:'):
+    kind = mojom.PendingReceiver(_Kind(kinds, spec[4:], scope))
+  elif spec.startswith('rma:'):
+    kind = mojom.PendingAssociatedRemote(_Kind(kinds, spec[4:], scope))
+  elif spec.startswith('rca:'):
+    kind = mojom.PendingAssociatedReceiver(_Kind(kinds, spec[4:], scope))
+  elif spec.startswith('m['):
+    # Isolate the two types from their brackets.
+
+    # It is not allowed to use map as key, so there shouldn't be nested ']'s
+    # inside the key type spec.
+    key_end = spec.find(']')
+    assert key_end != -1 and key_end < len(spec) - 1
+    assert spec[key_end + 1] == '[' and spec[-1] == ']'
+
+    first_kind = spec[2:key_end]
+    second_kind = spec[key_end + 2:-1]
+
+    kind = mojom.Map(
+        _Kind(kinds, first_kind, scope), _Kind(kinds, second_kind, scope))
+  else:
+    kind = mojom.Kind(spec)
+
+  kinds[spec] = kind
+  return kind
+
+
+def _Import(module, import_module):
+  # Copy the struct kinds from our imports into the current module.
+  importable_kinds = (mojom.Struct, mojom.Union, mojom.Enum, mojom.Interface,
+                      mojom.Feature)
+  for kind in import_module.kinds.values():
+    if (isinstance(kind, importable_kinds)
+        and kind.module.path == import_module.path):
+      module.kinds[kind.spec] = kind
+  # Ditto for values.
+  for value in import_module.values.values():
+    if value.module.path == import_module.path:
+      module.values[value.GetSpec()] = value
+
+  return import_module
+
+
+def _Feature(module, parsed_feature):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_feature: {ast.Feature} Parsed feature.
+
+  Returns:
+    {mojom.Feature} AST feature.
+  """
+  feature = mojom.Feature(module=module)
+  feature.mojom_name = parsed_feature.mojom_name
+  feature.spec = 'x:' + module.GetNamespacePrefix() + feature.mojom_name
+  module.kinds[feature.spec] = feature
+  feature.constants = []
+  _ProcessElements(
+      parsed_feature.mojom_name, parsed_feature.body, {
+          ast.Const:
+          lambda const: feature.constants.append(
+              _Constant(module, const, feature)),
+      })
+
+  feature.attributes = _AttributeListToDict(module, feature,
+                                            parsed_feature.attribute_list)
+  return feature
+
+
+def _Struct(module, parsed_struct):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_struct: {ast.Struct} Parsed struct.
+
+  Returns:
+    {mojom.Struct} AST struct.
+  """
+  struct = mojom.Struct(module=module)
+  struct.mojom_name = parsed_struct.mojom_name
+  struct.native_only = parsed_struct.body is None
+  struct.spec = 'x:' + module.GetNamespacePrefix() + struct.mojom_name
+  module.kinds[struct.spec] = struct
+  struct.enums = []
+  struct.constants = []
+  struct.fields_data = []
+  if not struct.native_only:
+    _ProcessElements(
+        parsed_struct.mojom_name, parsed_struct.body, {
+            ast.Enum:
+            lambda enum: struct.enums.append(_Enum(module, enum, struct)),
+            ast.Const:
+            lambda const: struct.constants.append(
+                _Constant(module, const, struct)),
+            ast.StructField:
+            struct.fields_data.append,
+        })
+
+  struct.attributes = _AttributeListToDict(module, struct,
+                                           parsed_struct.attribute_list)
+
+  # Enforce that a [Native] attribute is set to make native-only struct
+  # declarations more explicit.
+  if struct.native_only:
+    if not struct.attributes or not struct.attributes.get('Native', False):
+      raise Exception("Native-only struct declarations must include a " +
+                      "Native attribute.")
+
+  if struct.attributes and struct.attributes.get('CustomSerializer', False):
+    struct.custom_serializer = True
+
+  return struct
+
+
+def _Union(module, parsed_union):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_union: {ast.Union} Parsed union.
+
+  Returns:
+    {mojom.Union} AST union.
+  """
+  union = mojom.Union(module=module)
+  union.mojom_name = parsed_union.mojom_name
+  union.spec = 'x:' + module.GetNamespacePrefix() + union.mojom_name
+  module.kinds[union.spec] = union
+  # Stash fields parsed_union here temporarily.
+  union.fields_data = []
+  _ProcessElements(parsed_union.mojom_name, parsed_union.body,
+                   {ast.UnionField: union.fields_data.append})
+  union.attributes = _AttributeListToDict(module, union,
+                                          parsed_union.attribute_list)
+  return union
+
+
+def _StructField(module, parsed_field, struct):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_field: {ast.StructField} Parsed struct field.
+    struct: {mojom.Struct} Struct this field belongs to.
+
+  Returns:
+    {mojom.StructField} AST struct field.
+  """
+  field = mojom.StructField()
+  field.mojom_name = parsed_field.mojom_name
+  field.kind = _Kind(module.kinds, _MapKind(parsed_field.typename),
+                     (module.mojom_namespace, struct.mojom_name))
+  field.ordinal = parsed_field.ordinal.value if parsed_field.ordinal else None
+  field.default = _LookupValue(module, struct, field.kind,
+                               parsed_field.default_value)
+  field.attributes = _AttributeListToDict(module, field,
+                                          parsed_field.attribute_list)
+  return field
+
+
+def _UnionField(module, parsed_field, union):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_field: {ast.UnionField} Parsed union field.
+    union: {mojom.Union} Union this fields belong to.
+
+  Returns:
+    {mojom.UnionField} AST union.
+  """
+  field = mojom.UnionField()
+  field.mojom_name = parsed_field.mojom_name
+  # Disallow unions from being self-recursive.
+  parsed_typename = parsed_field.typename
+  if parsed_typename.endswith('?'):
+    parsed_typename = parsed_typename[:-1]
+  assert parsed_typename != union.mojom_name
+  field.kind = _Kind(module.kinds, _MapKind(parsed_field.typename),
+                     (module.mojom_namespace, union.mojom_name))
+  field.ordinal = parsed_field.ordinal.value if parsed_field.ordinal else None
+  field.default = None
+  field.attributes = _AttributeListToDict(module, field,
+                                          parsed_field.attribute_list)
+  if field.is_default and not mojom.IsNullableKind(field.kind) and \
+     not mojom.IsIntegralKind(field.kind):
+    raise Exception(
+        '[Default] field for union %s must be nullable or integral type.' %
+        union.mojom_name)
+  return field
+
+
+def _Parameter(module, parsed_param, interface):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_param: {ast.Parameter} Parsed parameter.
+    union: {mojom.Interface} Interface this parameter belongs to.
+
+  Returns:
+    {mojom.Parameter} AST parameter.
+  """
+  parameter = mojom.Parameter()
+  parameter.mojom_name = parsed_param.mojom_name
+  parameter.kind = _Kind(module.kinds, _MapKind(parsed_param.typename),
+                         (module.mojom_namespace, interface.mojom_name))
+  parameter.ordinal = (parsed_param.ordinal.value
+                       if parsed_param.ordinal else None)
+  parameter.default = None  # TODO(tibell): We never have these. Remove field?
+  parameter.attributes = _AttributeListToDict(module, parameter,
+                                              parsed_param.attribute_list)
+  return parameter
+
+
+def _Method(module, parsed_method, interface):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_method: {ast.Method} Parsed method.
+    interface: {mojom.Interface} Interface this method belongs to.
+
+  Returns:
+    {mojom.Method} AST method.
+  """
+  method = mojom.Method(
+      interface,
+      parsed_method.mojom_name,
+      ordinal=parsed_method.ordinal.value if parsed_method.ordinal else None)
+  method.parameters = list(
+      map(lambda parameter: _Parameter(module, parameter, interface),
+          parsed_method.parameter_list))
+  if parsed_method.response_parameter_list is not None:
+    method.response_parameters = list(
+        map(lambda parameter: _Parameter(module, parameter, interface),
+            parsed_method.response_parameter_list))
+  method.attributes = _AttributeListToDict(module, method,
+                                           parsed_method.attribute_list)
+
+  # Enforce that only methods with response can have a [Sync] attribute.
+  if method.sync and method.response_parameters is None:
+    raise Exception("Only methods with response can include a [Sync] "
+                    "attribute. If no response parameters are needed, you "
+                    "could use an empty response parameter list, i.e., "
+                    "\"=> ()\".")
+  # And only methods with the [Sync] attribute can specify [NoInterrupt].
+  if not method.allow_interrupt and not method.sync:
+    raise Exception("Only [Sync] methods can be marked [NoInterrupt].")
+
+  return method
+
+
+def _Interface(module, parsed_iface):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_iface: {ast.Interface} Parsed interface.
+
+  Returns:
+    {mojom.Interface} AST interface.
+  """
+  interface = mojom.Interface(module=module)
+  interface.mojom_name = parsed_iface.mojom_name
+  interface.spec = 'x:' + module.GetNamespacePrefix() + interface.mojom_name
+  module.kinds[interface.spec] = interface
+  interface.attributes = _AttributeListToDict(module, interface,
+                                              parsed_iface.attribute_list)
+  interface.enums = []
+  interface.constants = []
+  interface.methods_data = []
+  _ProcessElements(
+      parsed_iface.mojom_name, parsed_iface.body, {
+          ast.Enum:
+          lambda enum: interface.enums.append(_Enum(module, enum, interface)),
+          ast.Const:
+          lambda const: interface.constants.append(
+              _Constant(module, const, interface)),
+          ast.Method:
+          interface.methods_data.append,
+      })
+  return interface
+
+
+def _EnumField(module, enum, parsed_field):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    enum: {mojom.Enum} Enum this field belongs to.
+    parsed_field: {ast.EnumValue} Parsed enum value.
+
+  Returns:
+    {mojom.EnumField} AST enum field.
+  """
+  field = mojom.EnumField()
+  field.mojom_name = parsed_field.mojom_name
+  field.value = _LookupValue(module, enum, None, parsed_field.value)
+  field.attributes = _AttributeListToDict(module, field,
+                                          parsed_field.attribute_list)
+  value = mojom.EnumValue(module, enum, field)
+  module.values[value.GetSpec()] = value
+  return field
+
+
+def _ResolveNumericEnumValues(enum):
+  """
+  Given a reference to a mojom.Enum, resolves and assigns the numeric value of
+  each field, and also computes the min_value and max_value of the enum.
+  """
+
+  # map of <mojom_name> -> integral value
+  prev_value = -1
+  min_value = None
+  max_value = None
+  for field in enum.fields:
+    # This enum value is +1 the previous enum value (e.g: BEGIN).
+    if field.value is None:
+      prev_value += 1
+
+    # Integral value (e.g: BEGIN = -0x1).
+    elif isinstance(field.value, str):
+      prev_value = int(field.value, 0)
+
+    # Reference to a previous enum value (e.g: INIT = BEGIN).
+    elif isinstance(field.value, mojom.EnumValue):
+      prev_value = field.value.field.numeric_value
+    elif isinstance(field.value, mojom.ConstantValue):
+      constant = field.value.constant
+      kind = constant.kind
+      if not mojom.IsIntegralKind(kind) or mojom.IsBoolKind(kind):
+        raise ValueError('Enum values must be integers. %s is not an integer.' %
+                         constant.mojom_name)
+      prev_value = int(constant.value, 0)
+    else:
+      raise Exception('Unresolved enum value for %s' % field.value.GetSpec())
+
+    if prev_value in (-128, -127):
+      raise Exception(f'{field.mojom_name} in {enum.spec} has the value '
+                      f'{prev_value}, which is reserved for WTF::HashTrait\'s '
+                      'default enum specialization and may not be used.')
+    field.numeric_value = prev_value
+    if min_value is None or prev_value < min_value:
+      min_value = prev_value
+    if max_value is None or prev_value > max_value:
+      max_value = prev_value
+
+  enum.min_value = min_value
+  enum.max_value = max_value
+
+
+def _Enum(module, parsed_enum, parent_kind):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_enum: {ast.Enum} Parsed enum.
+
+  Returns:
+    {mojom.Enum} AST enum.
+  """
+  enum = mojom.Enum(module=module)
+  enum.mojom_name = parsed_enum.mojom_name
+  enum.native_only = parsed_enum.enum_value_list is None
+  mojom_name = enum.mojom_name
+  if parent_kind:
+    mojom_name = parent_kind.mojom_name + '.' + mojom_name
+  enum.spec = 'x:%s.%s' % (module.mojom_namespace, mojom_name)
+  enum.parent_kind = parent_kind
+  enum.attributes = _AttributeListToDict(module, enum,
+                                         parsed_enum.attribute_list)
+
+  if not enum.native_only:
+    enum.fields = list(
+        map(lambda field: _EnumField(module, enum, field),
+            parsed_enum.enum_value_list))
+    _ResolveNumericEnumValues(enum)
+    # TODO(https://crbug.com/731893): Require a default value to be
+    # specified.
+    for field in enum.fields:
+      if field.default:
+        if not enum.extensible:
+          raise Exception(
+              f'Non-extensible enum {enum.spec} may not specify a default')
+        if enum.default_field is not None:
+          raise Exception(f'Multiple [Default] enumerators in enum {enum.spec}')
+        enum.default_field = field
+    # While running the backwards compatibility check, ignore errors because the
+    # old version of the enum might not specify [Default].
+    if (enum.extensible and enum.default_field is None
+        and enum.spec not in _EXTENSIBLE_ENUMS_MISSING_DEFAULT
+        and not is_running_backwards_compatibility_check_hack):
+      raise Exception(
+          f'Extensible enum {enum.spec} must specify a [Default] enumerator')
+
+  module.kinds[enum.spec] = enum
+
+  # Enforce that a [Native] attribute is set to make native-only enum
+  # declarations more explicit.
+  if enum.native_only:
+    if not enum.attributes or not enum.attributes.get('Native', False):
+      raise Exception("Native-only enum declarations must include a " +
+                      "Native attribute.")
+
+  return enum
+
+
+def _Constant(module, parsed_const, parent_kind):
+  """
+  Args:
+    module: {mojom.Module} Module currently being constructed.
+    parsed_const: {ast.Const} Parsed constant.
+
+  Returns:
+    {mojom.Constant} AST constant.
+  """
+  constant = mojom.Constant()
+  constant.mojom_name = parsed_const.mojom_name
+  if parent_kind:
+    scope = (module.mojom_namespace, parent_kind.mojom_name)
+  else:
+    scope = (module.mojom_namespace, )
+  # TODO(mpcomplete): maybe we should only support POD kinds.
+  constant.kind = _Kind(module.kinds, _MapKind(parsed_const.typename), scope)
+  constant.parent_kind = parent_kind
+  constant.value = _LookupValue(module, parent_kind, constant.kind,
+                                parsed_const.value)
+
+  # Iteratively resolve this constant reference to a concrete value
+  while isinstance(constant.value, mojom.ConstantValue):
+    constant.value = constant.value.constant.value
+
+  value = mojom.ConstantValue(module, parent_kind, constant)
+  module.values[value.GetSpec()] = value
+  return constant
+
+
+def _CollectReferencedKinds(module, all_defined_kinds):
+  """
+  Takes a {mojom.Module} object and a list of all defined kinds within that
+  module, and enumerates the complete dict of user-defined mojom types
+  (as {mojom.Kind} objects) referenced by the module's own defined kinds (i.e.
+  as types of struct or union or interface parameters. The returned dict is
+  keyed by kind spec.
+  """
+
+  def extract_referenced_user_kinds(kind):
+    if mojom.IsArrayKind(kind):
+      return extract_referenced_user_kinds(kind.kind)
+    if mojom.IsMapKind(kind):
+      return (extract_referenced_user_kinds(kind.key_kind) +
+              extract_referenced_user_kinds(kind.value_kind))
+    if (mojom.IsInterfaceRequestKind(kind) or mojom.IsAssociatedKind(kind)
+        or mojom.IsPendingRemoteKind(kind)
+        or mojom.IsPendingReceiverKind(kind)):
+      return [kind.kind]
+    if mojom.IsStructKind(kind):
+      return [kind]
+    if (mojom.IsInterfaceKind(kind) or mojom.IsEnumKind(kind)
+        or mojom.IsUnionKind(kind)):
+      return [kind]
+    return []
+
+  def sanitize_kind(kind):
+    """Removes nullability from a kind"""
+    if kind.spec.startswith('?'):
+      return _Kind(module.kinds, kind.spec[1:], (module.mojom_namespace, ''))
+    return kind
+
+  referenced_user_kinds = {}
+  for defined_kind in all_defined_kinds:
+    if mojom.IsStructKind(defined_kind) or mojom.IsUnionKind(defined_kind):
+      for field in defined_kind.fields:
+        for referenced_kind in extract_referenced_user_kinds(field.kind):
+          sanitized_kind = sanitize_kind(referenced_kind)
+          referenced_user_kinds[sanitized_kind.spec] = sanitized_kind
+
+  # Also scan for references in parameter lists
+  for interface in module.interfaces:
+    for method in interface.methods:
+      for param in itertools.chain(method.parameters or [],
+                                   method.response_parameters or []):
+        for referenced_kind in extract_referenced_user_kinds(param.kind):
+          sanitized_kind = sanitize_kind(referenced_kind)
+          referenced_user_kinds[sanitized_kind.spec] = sanitized_kind
+  # Consts can reference imported enums.
+  for const in module.constants:
+    if not const.kind in mojom.PRIMITIVES:
+      sanitized_kind = sanitize_kind(const.kind)
+      referenced_user_kinds[sanitized_kind.spec] = sanitized_kind
+
+  return referenced_user_kinds
+
+
+def _AssignDefaultOrdinals(items):
+  """Assigns default ordinal values to a sequence of items if necessary."""
+  next_ordinal = 0
+  for item in items:
+    if item.ordinal is not None:
+      next_ordinal = item.ordinal + 1
+    else:
+      item.ordinal = next_ordinal
+      next_ordinal += 1
+
+
+def _AssertTypeIsStable(kind):
+  """Raises an error if a type is not stable, meaning it is composed of at least
+  one type that is not marked [Stable]."""
+
+  def assertDependencyIsStable(dependency):
+    if (mojom.IsEnumKind(dependency) or mojom.IsStructKind(dependency)
+        or mojom.IsUnionKind(dependency) or mojom.IsInterfaceKind(dependency)):
+      if not dependency.stable:
+        raise Exception(
+            '%s is marked [Stable] but cannot be stable because it depends on '
+            '%s, which is not marked [Stable].' %
+            (kind.mojom_name, dependency.mojom_name))
+    elif mojom.IsArrayKind(dependency) or mojom.IsAnyInterfaceKind(dependency):
+      assertDependencyIsStable(dependency.kind)
+    elif mojom.IsMapKind(dependency):
+      assertDependencyIsStable(dependency.key_kind)
+      assertDependencyIsStable(dependency.value_kind)
+
+  if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
+    for field in kind.fields:
+      assertDependencyIsStable(field.kind)
+  elif mojom.IsInterfaceKind(kind):
+    for method in kind.methods:
+      for param in method.param_struct.fields:
+        assertDependencyIsStable(param.kind)
+      if method.response_param_struct:
+        for response_param in method.response_param_struct.fields:
+          assertDependencyIsStable(response_param.kind)
+
+
+def _AssertStructIsValid(kind):
+  expected_ordinals = set(range(0, len(kind.fields)))
+  ordinals = set(map(lambda field: field.ordinal, kind.fields))
+  if ordinals != expected_ordinals:
+    raise Exception(
+        'Structs must use contiguous ordinals starting from 0. ' +
+        '{} is missing the following ordinals: {}.'.format(
+            kind.mojom_name, ', '.join(map(str, expected_ordinals - ordinals))))
+
+
+def _Module(tree, path, imports):
+  """
+  Args:
+    tree: {ast.Mojom} The parse tree.
+    path: {str} The path to the mojom file.
+    imports: {Dict[str, mojom.Module]} Mapping from filenames, as they appear in
+        the import list, to already processed modules. Used to process imports.
+
+  Returns:
+    {mojom.Module} An AST for the mojom.
+  """
+  module = mojom.Module(path=path)
+  module.kinds = {}
+  for kind in mojom.PRIMITIVES:
+    module.kinds[kind.spec] = kind
+
+  module.values = {}
+
+  module.mojom_namespace = tree.module.mojom_namespace[1] if tree.module else ''
+  # Imports must come first, because they add to module.kinds which is used
+  # by by the others.
+  module.imports = [
+      _Import(module, imports[imp.import_filename]) for imp in tree.import_list
+  ]
+  if tree.module and tree.module.attribute_list:
+    assert isinstance(tree.module.attribute_list, ast.AttributeList)
+    # TODO(vtl): Check for duplicate keys here.
+    module.attributes = dict((attribute.key, attribute.value)
+                             for attribute in tree.module.attribute_list)
+
+  filename = os.path.basename(path)
+  # First pass collects kinds.
+  module.constants = []
+  module.enums = []
+  module.structs = []
+  module.unions = []
+  module.interfaces = []
+  module.features = []
+
+  _ProcessElements(
+      filename, tree.definition_list, {
+          ast.Const:
+          lambda const: module.constants.append(_Constant(module, const, None)),
+          ast.Enum:
+          lambda enum: module.enums.append(_Enum(module, enum, None)),
+          ast.Struct:
+          lambda struct: module.structs.append(_Struct(module, struct)),
+          ast.Union:
+          lambda union: module.unions.append(_Union(module, union)),
+          ast.Interface:
+          lambda interface: module.interfaces.append(
+              _Interface(module, interface)),
+          ast.Feature:
+          lambda feature: module.features.append(_Feature(module, feature)),
+      })
+
+  # Second pass expands fields and methods. This allows fields and parameters
+  # to refer to kinds defined anywhere in the mojom.
+  all_defined_kinds = {}
+  for struct in module.structs:
+    struct.fields = list(
+        map(lambda field: _StructField(module, field, struct),
+            struct.fields_data))
+    _AssignDefaultOrdinals(struct.fields)
+    del struct.fields_data
+    all_defined_kinds[struct.spec] = struct
+    for enum in struct.enums:
+      all_defined_kinds[enum.spec] = enum
+
+  for feature in module.features:
+    all_defined_kinds[feature.spec] = feature
+
+  for union in module.unions:
+    union.fields = list(
+        map(lambda field: _UnionField(module, field, union), union.fields_data))
+    _AssignDefaultOrdinals(union.fields)
+    for field in union.fields:
+      if field.is_default:
+        if union.default_field is not None:
+          raise Exception('Multiple [Default] fields in union %s.' %
+                          union.mojom_name)
+        union.default_field = field
+    del union.fields_data
+    all_defined_kinds[union.spec] = union
+    if union.extensible and union.default_field is None:
+      raise Exception('Extensible union %s must specify a [Default] field' %
+                      union.mojom_name)
+
+  for interface in module.interfaces:
+    interface.methods = list(
+        map(lambda method: _Method(module, method, interface),
+            interface.methods_data))
+    _AssignDefaultOrdinals(interface.methods)
+    del interface.methods_data
+    all_defined_kinds[interface.spec] = interface
+    for enum in interface.enums:
+      all_defined_kinds[enum.spec] = enum
+  for enum in module.enums:
+    all_defined_kinds[enum.spec] = enum
+
+  all_referenced_kinds = _CollectReferencedKinds(module,
+                                                 all_defined_kinds.values())
+  imported_kind_specs = set(all_referenced_kinds.keys()).difference(
+      set(all_defined_kinds.keys()))
+  module.imported_kinds = OrderedDict((spec, all_referenced_kinds[spec])
+                                      for spec in sorted(imported_kind_specs))
+
+  generator.AddComputedData(module)
+  for iface in module.interfaces:
+    for method in iface.methods:
+      if method.param_struct:
+        _AssignDefaultOrdinals(method.param_struct.fields)
+      if method.response_param_struct:
+        _AssignDefaultOrdinals(method.response_param_struct.fields)
+
+  # Ensure that all types marked [Stable] are actually stable. Enums are
+  # automatically OK since they don't depend on other definitions.
+  for kinds in (module.structs, module.unions, module.interfaces):
+    for kind in kinds:
+      if kind.stable:
+        _AssertTypeIsStable(kind)
+
+  for kind in module.structs:
+    _AssertStructIsValid(kind)
+
+  return module
+
+
+def OrderedModule(tree, path, imports):
+  """Convert parse tree to AST module.
+
+  Args:
+    tree: {ast.Mojom} The parse tree.
+    path: {str} The path to the mojom file.
+    imports: {Dict[str, mojom.Module]} Mapping from filenames, as they appear in
+        the import list, to already processed modules. Used to process imports.
+
+  Returns:
+    {mojom.Module} An AST for the mojom.
+  """
+  module = _Module(tree, path, imports)
+  return module
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/translate_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/translate_unittest.py
new file mode 100644
index 00000000..b4fea924
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/generate/translate_unittest.py
@@ -0,0 +1,141 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+from mojom.generate import module as mojom
+from mojom.generate import translate
+from mojom.parse import ast
+
+class TranslateTest(unittest.TestCase):
+  """Tests |parser.Parse()|."""
+
+  def testSimpleArray(self):
+    """Tests a simple int32[]."""
+    # pylint: disable=W0212
+    self.assertEquals(translate._MapKind("int32[]"), "a:i32")
+
+  def testAssociativeArray(self):
+    """Tests a simple uint8{string}."""
+    # pylint: disable=W0212
+    self.assertEquals(translate._MapKind("uint8{string}"), "m[s][u8]")
+
+  def testLeftToRightAssociativeArray(self):
+    """Makes sure that parsing is done from right to left on the internal kinds
+       in the presence of an associative array."""
+    # pylint: disable=W0212
+    self.assertEquals(translate._MapKind("uint8[]{string}"), "m[s][a:u8]")
+
+  def testTranslateSimpleUnions(self):
+    """Makes sure that a simple union is translated correctly."""
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Union(
+            "SomeUnion", None,
+            ast.UnionBody([
+                ast.UnionField("a", None, None, "int32"),
+                ast.UnionField("b", None, None, "string")
+            ]))
+    ])
+
+    translation = translate.OrderedModule(tree, "mojom_tree", [])
+    self.assertEqual(1, len(translation.unions))
+
+    union = translation.unions[0]
+    self.assertTrue(isinstance(union, mojom.Union))
+    self.assertEqual("SomeUnion", union.mojom_name)
+    self.assertEqual(2, len(union.fields))
+    self.assertEqual("a", union.fields[0].mojom_name)
+    self.assertEqual(mojom.INT32.spec, union.fields[0].kind.spec)
+    self.assertEqual("b", union.fields[1].mojom_name)
+    self.assertEqual(mojom.STRING.spec, union.fields[1].kind.spec)
+
+  def testMapKindRaisesWithDuplicate(self):
+    """Verifies _MapTreeForType() raises when passed two values with the same
+       name."""
+    methods = [
+        ast.Method('dup', None, None, ast.ParameterList(), None),
+        ast.Method('dup', None, None, ast.ParameterList(), None)
+    ]
+    with self.assertRaises(Exception):
+      translate._ElemsOfType(methods, ast.Method, 'scope')
+
+  def testAssociatedKinds(self):
+    """Tests type spec translation of associated interfaces and requests."""
+    # pylint: disable=W0212
+    self.assertEquals(
+        translate._MapKind("asso<SomeInterface>?"), "?asso:x:SomeInterface")
+    self.assertEquals(translate._MapKind("rca<SomeInterface>?"),
+                      "?rca:x:SomeInterface")
+
+  def testSelfRecursiveUnions(self):
+    """Verifies _UnionField() raises when a union is self-recursive."""
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Union("SomeUnion", None,
+                  ast.UnionBody([ast.UnionField("a", None, None, "SomeUnion")]))
+    ])
+    with self.assertRaises(Exception):
+      translate.OrderedModule(tree, "mojom_tree", [])
+
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Union(
+            "SomeUnion", None,
+            ast.UnionBody([ast.UnionField("a", None, None, "SomeUnion?")]))
+    ])
+    with self.assertRaises(Exception):
+      translate.OrderedModule(tree, "mojom_tree", [])
+
+  def testDuplicateAttributesException(self):
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Union(
+            "FakeUnion",
+            ast.AttributeList([
+                ast.Attribute("key1", "value"),
+                ast.Attribute("key1", "value")
+            ]),
+            ast.UnionBody([
+                ast.UnionField("a", None, None, "int32"),
+                ast.UnionField("b", None, None, "string")
+            ]))
+    ])
+    with self.assertRaises(Exception):
+      translate.OrderedModule(tree, "mojom_tree", [])
+
+  def testEnumWithReservedValues(self):
+    """Verifies that assigning reserved values to enumerators fails."""
+    # -128 is reserved for the empty representation in WTF::HashTraits.
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Enum(
+            "MyEnum", None,
+            ast.EnumValueList([
+                ast.EnumValue('kReserved', None, '-128'),
+            ]))
+    ])
+    with self.assertRaises(Exception) as context:
+      translate.OrderedModule(tree, "mojom_tree", [])
+    self.assertIn("reserved for WTF::HashTrait", str(context.exception))
+
+    # -127 is reserved for the deleted representation in WTF::HashTraits.
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Enum(
+            "MyEnum", None,
+            ast.EnumValueList([
+                ast.EnumValue('kReserved', None, '-127'),
+            ]))
+    ])
+    with self.assertRaises(Exception) as context:
+      translate.OrderedModule(tree, "mojom_tree", [])
+    self.assertIn("reserved for WTF::HashTrait", str(context.exception))
+
+    # Implicitly assigning a reserved value should also fail.
+    tree = ast.Mojom(None, ast.ImportList(), [
+        ast.Enum(
+            "MyEnum", None,
+            ast.EnumValueList([
+                ast.EnumValue('kNotReserved', None, '-129'),
+                ast.EnumValue('kImplicitlyReserved', None, None),
+            ]))
+    ])
+    with self.assertRaises(Exception) as context:
+      translate.OrderedModule(tree, "mojom_tree", [])
+    self.assertIn("reserved for WTF::HashTrait", str(context.exception))
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/__init__.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/__init__.py
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/ast.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/ast.py
new file mode 100644
index 00000000..aae9cdb6
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/ast.py
@@ -0,0 +1,462 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Node classes for the AST for a Mojo IDL file."""
+
+# Note: For convenience of testing, you probably want to define __eq__() methods
+# for all node types; it's okay to be slightly lax (e.g., not compare filename
+# and lineno). You may also define __repr__() to help with analyzing test
+# failures, especially for more complex types.
+
+import os.path
+
+
+# Instance of 'NodeListBase' has no '_list_item_type' member (no-member)
+# pylint: disable=no-member
+
+
+class NodeBase:
+  """Base class for nodes in the AST."""
+
+  def __init__(self, filename=None, lineno=None):
+    self.filename = filename
+    self.lineno = lineno
+
+  def __eq__(self, other):
+    # We want strict comparison of the two object's types. Disable pylint's
+    # insistence upon recommending isinstance().
+    # pylint: disable=unidiomatic-typecheck
+    return type(self) == type(other)
+
+  # Make != the inverse of ==. (Subclasses shouldn't have to override this.)
+  def __ne__(self, other):
+    return not self == other
+
+
+# TODO(vtl): Some of this is complicated enough that it should be tested.
+class NodeListBase(NodeBase):
+  """Represents a list of other nodes, all having the same type. (This is meant
+  to be subclassed, with subclasses defining _list_item_type to be the class (or
+  classes, in a tuple) of the members of the list.)"""
+
+  def __init__(self, item_or_items=None, **kwargs):
+    super().__init__(**kwargs)
+    self.items = []
+    if item_or_items is None:
+      pass
+    elif isinstance(item_or_items, list):
+      for item in item_or_items:
+        assert isinstance(item, self._list_item_type)
+        self.Append(item)
+    else:
+      assert isinstance(item_or_items, self._list_item_type)
+      self.Append(item_or_items)
+
+  # Support iteration. For everything else, users should just access |items|
+  # directly. (We intentionally do NOT supply |__len__()| or |__nonzero__()|, so
+  # |bool(NodeListBase())| is true.)
+  def __iter__(self):
+    return self.items.__iter__()
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.items == other.items
+
+  # Implement this so that on failure, we get slightly more sensible output.
+  def __repr__(self):
+    return self.__class__.__name__ + "([" + \
+           ", ".join([repr(elem) for elem in self.items]) + "])"
+
+  def Insert(self, item):
+    """Inserts item at the front of the list."""
+
+    assert isinstance(item, self._list_item_type)
+    self.items.insert(0, item)
+    self._UpdateFilenameAndLineno()
+
+  def Append(self, item):
+    """Appends item to the end of the list."""
+
+    assert isinstance(item, self._list_item_type)
+    self.items.append(item)
+    self._UpdateFilenameAndLineno()
+
+  def _UpdateFilenameAndLineno(self):
+    if self.items:
+      self.filename = self.items[0].filename
+      self.lineno = self.items[0].lineno
+
+
+class Definition(NodeBase):
+  """Represents a definition of anything that has a global name (e.g., enums,
+  enum values, consts, structs, struct fields, interfaces). (This does not
+  include parameter definitions.) This class is meant to be subclassed."""
+
+  def __init__(self, mojom_name, **kwargs):
+    assert isinstance(mojom_name, str)
+    NodeBase.__init__(self, **kwargs)
+    self.mojom_name = mojom_name
+
+
+################################################################################
+
+
+class Attribute(NodeBase):
+  """Represents an attribute."""
+
+  def __init__(self, key, value, **kwargs):
+    assert isinstance(key, str)
+    super().__init__(**kwargs)
+    self.key = key
+    self.value = value
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.key == other.key and \
+           self.value == other.value
+
+
+class AttributeList(NodeListBase):
+  """Represents a list attributes."""
+
+  _list_item_type = Attribute
+
+
+class Const(Definition):
+  """Represents a const definition."""
+
+  def __init__(self, mojom_name, attribute_list, typename, value, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    # The typename is currently passed through as a string.
+    assert isinstance(typename, str)
+    # The value is either a literal (currently passed through as a string) or a
+    # "wrapped identifier".
+    assert isinstance(value, (tuple, str))
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.typename = typename
+    self.value = value
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.typename == other.typename and \
+           self.value == other.value
+
+
+class Enum(Definition):
+  """Represents an enum definition."""
+
+  def __init__(self, mojom_name, attribute_list, enum_value_list, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert enum_value_list is None or isinstance(enum_value_list, EnumValueList)
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.enum_value_list = enum_value_list
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.enum_value_list == other.enum_value_list
+
+
+class EnumValue(Definition):
+  """Represents a definition of an enum value."""
+
+  def __init__(self, mojom_name, attribute_list, value, **kwargs):
+    # The optional value is either an int (which is current a string) or a
+    # "wrapped identifier".
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert value is None or isinstance(value, (tuple, str))
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.value = value
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.value == other.value
+
+
+class EnumValueList(NodeListBase):
+  """Represents a list of enum value definitions (i.e., the "body" of an enum
+  definition)."""
+
+  _list_item_type = EnumValue
+
+
+class Feature(Definition):
+  """Represents a runtime feature definition."""
+  def __init__(self, mojom_name, attribute_list, body, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert isinstance(body, FeatureBody) or body is None
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.body = body
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.body == other.body
+
+  def __repr__(self):
+    return "Feature(mojom_name = %s, attribute_list = %s, body = %s)" % (
+        self.mojom_name, self.attribute_list, self.body)
+
+
+# This needs to be declared after `FeatureConst` and `FeatureField`.
+class FeatureBody(NodeListBase):
+  """Represents the body of (i.e., list of definitions inside) a feature."""
+
+  # Features are compile time helpers so all fields are initializers/consts
+  # for the underlying platform feature type.
+  _list_item_type = (Const)
+
+
+class Import(NodeBase):
+  """Represents an import statement."""
+
+  def __init__(self, attribute_list, import_filename, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert isinstance(import_filename, str)
+    super().__init__(**kwargs)
+    self.attribute_list = attribute_list
+    # TODO(crbug.com/953884): Use pathlib once we're migrated fully to Python 3.
+    self.import_filename = os.path.normpath(import_filename).replace('\\', '/')
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.import_filename == other.import_filename
+
+
+class ImportList(NodeListBase):
+  """Represents a list (i.e., sequence) of import statements."""
+
+  _list_item_type = Import
+
+
+class Interface(Definition):
+  """Represents an interface definition."""
+
+  def __init__(self, mojom_name, attribute_list, body, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert isinstance(body, InterfaceBody)
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.body = body
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.body == other.body
+
+
+class Method(Definition):
+  """Represents a method definition."""
+
+  def __init__(self, mojom_name, attribute_list, ordinal, parameter_list,
+               response_parameter_list, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert ordinal is None or isinstance(ordinal, Ordinal)
+    assert isinstance(parameter_list, ParameterList)
+    assert response_parameter_list is None or \
+           isinstance(response_parameter_list, ParameterList)
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.ordinal = ordinal
+    self.parameter_list = parameter_list
+    self.response_parameter_list = response_parameter_list
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.ordinal == other.ordinal and \
+           self.parameter_list == other.parameter_list and \
+           self.response_parameter_list == other.response_parameter_list
+
+
+# This needs to be declared after |Method|.
+class InterfaceBody(NodeListBase):
+  """Represents the body of (i.e., list of definitions inside) an interface."""
+
+  _list_item_type = (Const, Enum, Method)
+
+
+class Module(NodeBase):
+  """Represents a module statement."""
+
+  def __init__(self, mojom_namespace, attribute_list, **kwargs):
+    # |mojom_namespace| is either none or a "wrapped identifier".
+    assert mojom_namespace is None or isinstance(mojom_namespace, tuple)
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    super().__init__(**kwargs)
+    self.mojom_namespace = mojom_namespace
+    self.attribute_list = attribute_list
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.mojom_namespace == other.mojom_namespace and \
+           self.attribute_list == other.attribute_list
+
+
+class Mojom(NodeBase):
+  """Represents an entire .mojom file. (This is the root node.)"""
+
+  def __init__(self, module, import_list, definition_list, **kwargs):
+    assert module is None or isinstance(module, Module)
+    assert isinstance(import_list, ImportList)
+    assert isinstance(definition_list, list)
+    super().__init__(**kwargs)
+    self.module = module
+    self.import_list = import_list
+    self.definition_list = definition_list
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.module == other.module and \
+           self.import_list == other.import_list and \
+           self.definition_list == other.definition_list
+
+  def __repr__(self):
+    return "%s(%r, %r, %r)" % (self.__class__.__name__, self.module,
+                               self.import_list, self.definition_list)
+
+
+class Ordinal(NodeBase):
+  """Represents an ordinal value labeling, e.g., a struct field."""
+
+  def __init__(self, value, **kwargs):
+    assert isinstance(value, int)
+    super().__init__(**kwargs)
+    self.value = value
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.value == other.value
+
+
+class Parameter(NodeBase):
+  """Represents a method request or response parameter."""
+
+  def __init__(self, mojom_name, attribute_list, ordinal, typename, **kwargs):
+    assert isinstance(mojom_name, str)
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert ordinal is None or isinstance(ordinal, Ordinal)
+    assert isinstance(typename, str)
+    super().__init__(**kwargs)
+    self.mojom_name = mojom_name
+    self.attribute_list = attribute_list
+    self.ordinal = ordinal
+    self.typename = typename
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.mojom_name == other.mojom_name and \
+           self.attribute_list == other.attribute_list and \
+           self.ordinal == other.ordinal and \
+           self.typename == other.typename
+
+
+class ParameterList(NodeListBase):
+  """Represents a list of (method request or response) parameters."""
+
+  _list_item_type = Parameter
+
+
+class Struct(Definition):
+  """Represents a struct definition."""
+
+  def __init__(self, mojom_name, attribute_list, body, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert isinstance(body, StructBody) or body is None
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.body = body
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.body == other.body
+
+  def __repr__(self):
+    return "Struct(mojom_name = %s, attribute_list = %s, body = %s)" % (
+        self.mojom_name, self.attribute_list, self.body)
+
+
+class StructField(Definition):
+  """Represents a struct field definition."""
+
+  def __init__(self, mojom_name, attribute_list, ordinal, typename,
+               default_value, **kwargs):
+    assert isinstance(mojom_name, str)
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert ordinal is None or isinstance(ordinal, Ordinal)
+    assert isinstance(typename, str)
+    # The optional default value is currently either a value as a string or a
+    # "wrapped identifier".
+    assert default_value is None or isinstance(default_value, (str, tuple))
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.ordinal = ordinal
+    self.typename = typename
+    self.default_value = default_value
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.ordinal == other.ordinal and \
+           self.typename == other.typename and \
+           self.default_value == other.default_value
+
+  def __repr__(self):
+    return ("StructField(mojom_name = %s, attribute_list = %s, ordinal = %s, "
+            "typename = %s, default_value = %s") % (
+                self.mojom_name, self.attribute_list, self.ordinal,
+                self.typename, self.default_value)
+
+
+# This needs to be declared after |StructField|.
+class StructBody(NodeListBase):
+  """Represents the body of (i.e., list of definitions inside) a struct."""
+
+  _list_item_type = (Const, Enum, StructField)
+
+
+class Union(Definition):
+  """Represents a union definition."""
+
+  def __init__(self, mojom_name, attribute_list, body, **kwargs):
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert isinstance(body, UnionBody)
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.body = body
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.body == other.body
+
+
+class UnionField(Definition):
+  def __init__(self, mojom_name, attribute_list, ordinal, typename, **kwargs):
+    assert isinstance(mojom_name, str)
+    assert attribute_list is None or isinstance(attribute_list, AttributeList)
+    assert ordinal is None or isinstance(ordinal, Ordinal)
+    assert isinstance(typename, str)
+    super().__init__(mojom_name, **kwargs)
+    self.attribute_list = attribute_list
+    self.ordinal = ordinal
+    self.typename = typename
+
+  def __eq__(self, other):
+    return super().__eq__(other) and \
+           self.attribute_list == other.attribute_list and \
+           self.ordinal == other.ordinal and \
+           self.typename == other.typename
+
+
+class UnionBody(NodeListBase):
+
+  _list_item_type = UnionField
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/ast_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/ast_unittest.py
new file mode 100644
index 00000000..b289f7b1
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/ast_unittest.py
@@ -0,0 +1,115 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+from mojom.parse import ast
+
+class _TestNode(ast.NodeBase):
+  """Node type for tests."""
+
+  def __init__(self, value, **kwargs):
+    super().__init__(**kwargs)
+    self.value = value
+
+  def __eq__(self, other):
+    return super().__eq__(other) and self.value == other.value
+
+class _TestNodeList(ast.NodeListBase):
+  """Node list type for tests."""
+
+  _list_item_type = _TestNode
+
+class ASTTest(unittest.TestCase):
+  """Tests various AST classes."""
+
+  def testNodeBase(self):
+    # Test |__eq__()|; this is only used for testing, where we want to do
+    # comparison by value and ignore filenames/line numbers (for convenience).
+    node1 = ast.NodeBase(filename="hello.mojom", lineno=123)
+    node2 = ast.NodeBase()
+    self.assertEquals(node1, node2)
+    self.assertEquals(node2, node1)
+
+    # Check that |__ne__()| just defers to |__eq__()| properly.
+    self.assertFalse(node1 != node2)
+    self.assertFalse(node2 != node1)
+
+    # Check that |filename| and |lineno| are set properly (and are None by
+    # default).
+    self.assertEquals(node1.filename, "hello.mojom")
+    self.assertEquals(node1.lineno, 123)
+    self.assertIsNone(node2.filename)
+    self.assertIsNone(node2.lineno)
+
+    # |NodeBase|'s |__eq__()| should compare types (and a subclass's |__eq__()|
+    # should first defer to its superclass's).
+    node3 = _TestNode(123)
+    self.assertNotEqual(node1, node3)
+    self.assertNotEqual(node3, node1)
+    # Also test |__eq__()| directly.
+    self.assertFalse(node1 == node3)
+    self.assertFalse(node3 == node1)
+
+    node4 = _TestNode(123, filename="world.mojom", lineno=123)
+    self.assertEquals(node4, node3)
+    node5 = _TestNode(456)
+    self.assertNotEquals(node5, node4)
+
+  def testNodeListBase(self):
+    node1 = _TestNode(1, filename="foo.mojom", lineno=1)
+    # Equal to, but not the same as, |node1|:
+    node1b = _TestNode(1, filename="foo.mojom", lineno=1)
+    node2 = _TestNode(2, filename="foo.mojom", lineno=2)
+
+    nodelist1 = _TestNodeList()  # Contains: (empty).
+    self.assertEquals(nodelist1, nodelist1)
+    self.assertEquals(nodelist1.items, [])
+    self.assertIsNone(nodelist1.filename)
+    self.assertIsNone(nodelist1.lineno)
+
+    nodelist2 = _TestNodeList(node1)  # Contains: 1.
+    self.assertEquals(nodelist2, nodelist2)
+    self.assertEquals(nodelist2.items, [node1])
+    self.assertNotEqual(nodelist2, nodelist1)
+    self.assertEquals(nodelist2.filename, "foo.mojom")
+    self.assertEquals(nodelist2.lineno, 1)
+
+    nodelist3 = _TestNodeList([node2])  # Contains: 2.
+    self.assertEquals(nodelist3.items, [node2])
+    self.assertNotEqual(nodelist3, nodelist1)
+    self.assertNotEqual(nodelist3, nodelist2)
+    self.assertEquals(nodelist3.filename, "foo.mojom")
+    self.assertEquals(nodelist3.lineno, 2)
+
+    nodelist1.Append(node1b)  # Contains: 1.
+    self.assertEquals(nodelist1.items, [node1])
+    self.assertEquals(nodelist1, nodelist2)
+    self.assertNotEqual(nodelist1, nodelist3)
+    self.assertEquals(nodelist1.filename, "foo.mojom")
+    self.assertEquals(nodelist1.lineno, 1)
+
+    nodelist1.Append(node2)  # Contains: 1, 2.
+    self.assertEquals(nodelist1.items, [node1, node2])
+    self.assertNotEqual(nodelist1, nodelist2)
+    self.assertNotEqual(nodelist1, nodelist3)
+    self.assertEquals(nodelist1.lineno, 1)
+
+    nodelist2.Append(node2)  # Contains: 1, 2.
+    self.assertEquals(nodelist2.items, [node1, node2])
+    self.assertEquals(nodelist2, nodelist1)
+    self.assertNotEqual(nodelist2, nodelist3)
+    self.assertEquals(nodelist2.lineno, 1)
+
+    nodelist3.Insert(node1)  # Contains: 1, 2.
+    self.assertEquals(nodelist3.items, [node1, node2])
+    self.assertEquals(nodelist3, nodelist1)
+    self.assertEquals(nodelist3, nodelist2)
+    self.assertEquals(nodelist3.lineno, 1)
+
+    # Test iteration:
+    i = 1
+    for item in nodelist1:
+      self.assertEquals(item.value, i)
+      i += 1
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/conditional_features.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/conditional_features.py
new file mode 100644
index 00000000..9687edbf
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/conditional_features.py
@@ -0,0 +1,83 @@
+# Copyright 2018 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Helpers for processing conditionally enabled features in a mojom."""
+
+from mojom.error import Error
+from mojom.parse import ast
+
+
+class EnableIfError(Error):
+  """ Class for errors from ."""
+
+  def __init__(self, filename, message, lineno=None):
+    Error.__init__(self, filename, message, lineno=lineno, addenda=None)
+
+
+def _IsEnabled(definition, enabled_features):
+  """Returns true if a definition is enabled.
+
+  A definition is enabled if it has no EnableIf/EnableIfNot attribute.
+  It is retained if it has an EnableIf attribute and the attribute is in
+  enabled_features. It is retained if it has an EnableIfNot attribute and the
+  attribute is not in enabled features.
+  """
+  if not hasattr(definition, "attribute_list"):
+    return True
+  if not definition.attribute_list:
+    return True
+
+  already_defined = False
+  for a in definition.attribute_list:
+    if a.key == 'EnableIf' or a.key == 'EnableIfNot':
+      if already_defined:
+        raise EnableIfError(
+            definition.filename,
+            "EnableIf/EnableIfNot attribute may only be set once per field.",
+            definition.lineno)
+      already_defined = True
+
+  for attribute in definition.attribute_list:
+    if attribute.key == 'EnableIf' and attribute.value not in enabled_features:
+      return False
+    if attribute.key == 'EnableIfNot' and attribute.value in enabled_features:
+      return False
+  return True
+
+
+def _FilterDisabledFromNodeList(node_list, enabled_features):
+  if not node_list:
+    return
+  assert isinstance(node_list, ast.NodeListBase)
+  node_list.items = [
+      item for item in node_list.items if _IsEnabled(item, enabled_features)
+  ]
+  for item in node_list.items:
+    _FilterDefinition(item, enabled_features)
+
+
+def _FilterDefinition(definition, enabled_features):
+  """Filters definitions with a body."""
+  if isinstance(definition, ast.Enum):
+    _FilterDisabledFromNodeList(definition.enum_value_list, enabled_features)
+  elif isinstance(definition, ast.Method):
+    _FilterDisabledFromNodeList(definition.parameter_list, enabled_features)
+    _FilterDisabledFromNodeList(definition.response_parameter_list,
+                                enabled_features)
+  elif isinstance(definition,
+                  (ast.Interface, ast.Struct, ast.Union, ast.Feature)):
+    _FilterDisabledFromNodeList(definition.body, enabled_features)
+
+
+def RemoveDisabledDefinitions(mojom, enabled_features):
+  """Removes conditionally disabled definitions from a Mojom node."""
+  mojom.import_list = ast.ImportList([
+      imported_file for imported_file in mojom.import_list
+      if _IsEnabled(imported_file, enabled_features)
+  ])
+  mojom.definition_list = [
+      definition for definition in mojom.definition_list
+      if _IsEnabled(definition, enabled_features)
+  ]
+  for definition in mojom.definition_list:
+    _FilterDefinition(definition, enabled_features)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/conditional_features_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/conditional_features_unittest.py
new file mode 100644
index 00000000..cca1764b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/conditional_features_unittest.py
@@ -0,0 +1,376 @@
+# Copyright 2018 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import importlib.util
+import os
+import sys
+import unittest
+
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, tail = os.path.split(path)
+    assert tail
+    if tail == dirname:
+      return path
+
+try:
+  importlib.util.find_spec("mojom")
+except ImportError:
+  sys.path.append(os.path.join(_GetDirAbove('pylib'), 'pylib'))
+import mojom.parse.ast as ast
+import mojom.parse.conditional_features as conditional_features
+import mojom.parse.parser as parser
+
+ENABLED_FEATURES = frozenset({'red', 'green', 'blue'})
+
+class ConditionalFeaturesTest(unittest.TestCase):
+  """Tests |mojom.parse.conditional_features|."""
+
+  def parseAndAssertEqual(self, source, expected_source):
+    definition = parser.Parse(source, "my_file.mojom")
+    conditional_features.RemoveDisabledDefinitions(definition, ENABLED_FEATURES)
+    expected = parser.Parse(expected_source, "my_file.mojom")
+    self.assertEquals(definition, expected)
+
+  def testFilterConst(self):
+    """Test that Consts are correctly filtered."""
+    const_source = """
+      [EnableIf=blue]
+      const int kMyConst1 = 1;
+      [EnableIf=orange]
+      const double kMyConst2 = 2;
+      const int kMyConst3 = 3;
+    """
+    expected_source = """
+      [EnableIf=blue]
+      const int kMyConst1 = 1;
+      const int kMyConst3 = 3;
+    """
+    self.parseAndAssertEqual(const_source, expected_source)
+
+  def testFilterIfNotConst(self):
+    """Test that Consts are correctly filtered."""
+    const_source = """
+      [EnableIfNot=blue]
+      const int kMyConst1 = 1;
+      [EnableIfNot=orange]
+      const double kMyConst2 = 2;
+      [EnableIf=blue]
+      const int kMyConst3 = 3;
+      [EnableIfNot=blue]
+      const int kMyConst4 = 4;
+      [EnableIfNot=purple]
+      const int kMyConst5 = 5;
+    """
+    expected_source = """
+      [EnableIfNot=orange]
+      const double kMyConst2 = 2;
+      [EnableIf=blue]
+      const int kMyConst3 = 3;
+      [EnableIfNot=purple]
+      const int kMyConst5 = 5;
+    """
+    self.parseAndAssertEqual(const_source, expected_source)
+
+  def testFilterIfNotMultipleConst(self):
+    """Test that Consts are correctly filtered."""
+    const_source = """
+      [EnableIfNot=blue]
+      const int kMyConst1 = 1;
+      [EnableIfNot=orange]
+      const double kMyConst2 = 2;
+      [EnableIfNot=orange]
+      const int kMyConst3 = 3;
+    """
+    expected_source = """
+      [EnableIfNot=orange]
+      const double kMyConst2 = 2;
+      [EnableIfNot=orange]
+      const int kMyConst3 = 3;
+    """
+    self.parseAndAssertEqual(const_source, expected_source)
+
+  def testFilterEnum(self):
+    """Test that EnumValues are correctly filtered from an Enum."""
+    enum_source = """
+      enum MyEnum {
+        [EnableIf=purple]
+        VALUE1,
+        [EnableIf=blue]
+        VALUE2,
+        VALUE3,
+      };
+    """
+    expected_source = """
+      enum MyEnum {
+        [EnableIf=blue]
+        VALUE2,
+        VALUE3
+      };
+    """
+    self.parseAndAssertEqual(enum_source, expected_source)
+
+  def testFilterImport(self):
+    """Test that imports are correctly filtered from a Mojom."""
+    import_source = """
+      [EnableIf=blue]
+      import "foo.mojom";
+      import "bar.mojom";
+      [EnableIf=purple]
+      import "baz.mojom";
+    """
+    expected_source = """
+      [EnableIf=blue]
+      import "foo.mojom";
+      import "bar.mojom";
+    """
+    self.parseAndAssertEqual(import_source, expected_source)
+
+  def testFilterIfNotImport(self):
+    """Test that imports are correctly filtered from a Mojom."""
+    import_source = """
+      [EnableIf=blue]
+      import "foo.mojom";
+      [EnableIfNot=purple]
+      import "bar.mojom";
+      [EnableIfNot=green]
+      import "baz.mojom";
+    """
+    expected_source = """
+      [EnableIf=blue]
+      import "foo.mojom";
+      [EnableIfNot=purple]
+      import "bar.mojom";
+    """
+    self.parseAndAssertEqual(import_source, expected_source)
+
+  def testFilterInterface(self):
+    """Test that definitions are correctly filtered from an Interface."""
+    interface_source = """
+      interface MyInterface {
+        [EnableIf=blue]
+        enum MyEnum {
+          [EnableIf=purple]
+          VALUE1,
+          VALUE2,
+        };
+        [EnableIf=blue]
+        const int32 kMyConst = 123;
+        [EnableIf=purple]
+        MyMethod();
+      };
+    """
+    expected_source = """
+      interface MyInterface {
+        [EnableIf=blue]
+        enum MyEnum {
+          VALUE2,
+        };
+        [EnableIf=blue]
+        const int32 kMyConst = 123;
+      };
+    """
+    self.parseAndAssertEqual(interface_source, expected_source)
+
+  def testFilterMethod(self):
+    """Test that Parameters are correctly filtered from a Method."""
+    method_source = """
+      interface MyInterface {
+        [EnableIf=blue]
+        MyMethod([EnableIf=purple] int32 a) => ([EnableIf=red] int32 b);
+      };
+    """
+    expected_source = """
+      interface MyInterface {
+        [EnableIf=blue]
+        MyMethod() => ([EnableIf=red] int32 b);
+      };
+    """
+    self.parseAndAssertEqual(method_source, expected_source)
+
+  def testFilterStruct(self):
+    """Test that definitions are correctly filtered from a Struct."""
+    struct_source = """
+      struct MyStruct {
+        [EnableIf=blue]
+        enum MyEnum {
+          VALUE1,
+          [EnableIf=purple]
+          VALUE2,
+        };
+        [EnableIf=yellow]
+        const double kMyConst = 1.23;
+        [EnableIf=green]
+        int32 a;
+        double b;
+        [EnableIf=purple]
+        int32 c;
+        [EnableIf=blue]
+        double d;
+        int32 e;
+        [EnableIf=orange]
+        double f;
+      };
+    """
+    expected_source = """
+      struct MyStruct {
+        [EnableIf=blue]
+        enum MyEnum {
+          VALUE1,
+        };
+        [EnableIf=green]
+        int32 a;
+        double b;
+        [EnableIf=blue]
+        double d;
+        int32 e;
+      };
+    """
+    self.parseAndAssertEqual(struct_source, expected_source)
+
+  def testFilterIfNotStruct(self):
+    """Test that definitions are correctly filtered from a Struct."""
+    struct_source = """
+      struct MyStruct {
+        [EnableIf=blue]
+        enum MyEnum {
+          VALUE1,
+          [EnableIfNot=red]
+          VALUE2,
+        };
+        [EnableIfNot=yellow]
+        const double kMyConst = 1.23;
+        [EnableIf=green]
+        int32 a;
+        double b;
+        [EnableIfNot=purple]
+        int32 c;
+        [EnableIf=blue]
+        double d;
+        int32 e;
+        [EnableIfNot=red]
+        double f;
+      };
+    """
+    expected_source = """
+      struct MyStruct {
+        [EnableIf=blue]
+        enum MyEnum {
+          VALUE1,
+        };
+        [EnableIfNot=yellow]
+        const double kMyConst = 1.23;
+        [EnableIf=green]
+        int32 a;
+        double b;
+        [EnableIfNot=purple]
+        int32 c;
+        [EnableIf=blue]
+        double d;
+        int32 e;
+      };
+    """
+    self.parseAndAssertEqual(struct_source, expected_source)
+
+  def testFilterUnion(self):
+    """Test that UnionFields are correctly filtered from a Union."""
+    union_source = """
+      union MyUnion {
+        [EnableIf=yellow]
+        int32 a;
+        [EnableIf=red]
+        bool b;
+      };
+    """
+    expected_source = """
+      union MyUnion {
+        [EnableIf=red]
+        bool b;
+      };
+    """
+    self.parseAndAssertEqual(union_source, expected_source)
+
+  def testSameNameFields(self):
+    mojom_source = """
+      enum Foo {
+        [EnableIf=red]
+        VALUE1 = 5,
+        [EnableIf=yellow]
+        VALUE1 = 6,
+      };
+      [EnableIf=red]
+      const double kMyConst = 1.23;
+      [EnableIf=yellow]
+      const double kMyConst = 4.56;
+    """
+    expected_source = """
+      enum Foo {
+        [EnableIf=red]
+        VALUE1 = 5,
+      };
+      [EnableIf=red]
+      const double kMyConst = 1.23;
+    """
+    self.parseAndAssertEqual(mojom_source, expected_source)
+
+  def testFeaturesWithEnableIf(self):
+    mojom_source = """
+      feature Foo {
+        const string name = "FooFeature";
+        [EnableIf=red]
+        const bool default_state = false;
+        [EnableIf=yellow]
+        const bool default_state = true;
+      };
+    """
+    expected_source = """
+      feature Foo {
+        const string name = "FooFeature";
+        [EnableIf=red]
+        const bool default_state = false;
+      };
+    """
+    self.parseAndAssertEqual(mojom_source, expected_source)
+
+  def testMultipleEnableIfs(self):
+    source = """
+      enum Foo {
+        [EnableIf=red,EnableIf=yellow]
+        kBarValue = 5,
+      };
+    """
+    definition = parser.Parse(source, "my_file.mojom")
+    self.assertRaises(conditional_features.EnableIfError,
+                      conditional_features.RemoveDisabledDefinitions,
+                      definition, ENABLED_FEATURES)
+
+  def testMultipleEnableIfs(self):
+    source = """
+      enum Foo {
+        [EnableIf=red,EnableIfNot=yellow]
+        kBarValue = 5,
+      };
+    """
+    definition = parser.Parse(source, "my_file.mojom")
+    self.assertRaises(conditional_features.EnableIfError,
+                      conditional_features.RemoveDisabledDefinitions,
+                      definition, ENABLED_FEATURES)
+
+  def testMultipleEnableIfs(self):
+    source = """
+      enum Foo {
+        [EnableIfNot=red,EnableIfNot=yellow]
+        kBarValue = 5,
+      };
+    """
+    definition = parser.Parse(source, "my_file.mojom")
+    self.assertRaises(conditional_features.EnableIfError,
+                      conditional_features.RemoveDisabledDefinitions,
+                      definition, ENABLED_FEATURES)
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/lexer.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/lexer.py
new file mode 100644
index 00000000..00136a8b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/lexer.py
@@ -0,0 +1,249 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os.path
+import sys
+
+from mojom import fileutil
+from mojom.error import Error
+
+fileutil.AddLocalRepoThirdPartyDirToModulePath()
+from ply.lex import TOKEN
+
+
+class LexError(Error):
+  """Class for errors from the lexer."""
+
+  def __init__(self, filename, message, lineno):
+    Error.__init__(self, filename, message, lineno=lineno)
+
+
+# We have methods which look like they could be functions:
+# pylint: disable=R0201
+class Lexer:
+  def __init__(self, filename):
+    self.filename = filename
+
+  ######################--   PRIVATE   --######################
+
+  ##
+  ## Internal auxiliary methods
+  ##
+  def _error(self, msg, token):
+    raise LexError(self.filename, msg, token.lineno)
+
+  ##
+  ## Reserved keywords
+  ##
+  keywords = (
+      'HANDLE',
+      'IMPORT',
+      'MODULE',
+      'STRUCT',
+      'UNION',
+      'INTERFACE',
+      'ENUM',
+      'CONST',
+      'TRUE',
+      'FALSE',
+      'DEFAULT',
+      'ARRAY',
+      'MAP',
+      'ASSOCIATED',
+      'PENDING_REMOTE',
+      'PENDING_RECEIVER',
+      'PENDING_ASSOCIATED_REMOTE',
+      'PENDING_ASSOCIATED_RECEIVER',
+      'FEATURE',
+  )
+
+  keyword_map = {}
+  for keyword in keywords:
+    keyword_map[keyword.lower()] = keyword
+
+  ##
+  ## All the tokens recognized by the lexer
+  ##
+  tokens = keywords + (
+      # Identifiers
+      'NAME',
+
+      # Constants
+      'ORDINAL',
+      'INT_CONST_DEC',
+      'INT_CONST_HEX',
+      'FLOAT_CONST',
+
+      # String literals
+      'STRING_LITERAL',
+
+      # Operators
+      'MINUS',
+      'PLUS',
+      'QSTN',
+
+      # Assignment
+      'EQUALS',
+
+      # Request / response
+      'RESPONSE',
+
+      # Delimiters
+      'LPAREN',
+      'RPAREN',  # ( )
+      'LBRACKET',
+      'RBRACKET',  # [ ]
+      'LBRACE',
+      'RBRACE',  # { }
+      'LANGLE',
+      'RANGLE',  # < >
+      'SEMI',  # ;
+      'COMMA',
+      'DOT'  # , .
+  )
+
+  ##
+  ## Regexes for use in tokens
+  ##
+
+  # valid C identifiers (K&R2: A.2.3)
+  identifier = r'[a-zA-Z_][0-9a-zA-Z_]*'
+
+  hex_prefix = '0[xX]'
+  hex_digits = '[0-9a-fA-F]+'
+
+  # integer constants (K&R2: A.2.5.1)
+  decimal_constant = '0|([1-9][0-9]*)'
+  hex_constant = hex_prefix + hex_digits
+  # Don't allow octal constants (even invalid octal).
+  octal_constant_disallowed = '0[0-9]+'
+
+  # character constants (K&R2: A.2.5.2)
+  # Note: a-zA-Z and '.-~^_!=&;,' are allowed as escape chars to support #line
+  # directives with Windows paths as filenames (..\..\dir\file)
+  # For the same reason, decimal_escape allows all digit sequences. We want to
+  # parse all correct code, even if it means to sometimes parse incorrect
+  # code.
+  #
+  simple_escape = r"""([a-zA-Z._~!=&\^\-\\?'"])"""
+  decimal_escape = r"""(\d+)"""
+  hex_escape = r"""(x[0-9a-fA-F]+)"""
+  bad_escape = r"""([\\][^a-zA-Z._~^!=&\^\-\\?'"x0-7])"""
+
+  escape_sequence = \
+      r"""(\\("""+simple_escape+'|'+decimal_escape+'|'+hex_escape+'))'
+
+  # string literals (K&R2: A.2.6)
+  string_char = r"""([^"\\\n]|""" + escape_sequence + ')'
+  string_literal = '"' + string_char + '*"'
+  bad_string_literal = '"' + string_char + '*' + bad_escape + string_char + '*"'
+
+  # floating constants (K&R2: A.2.5.3)
+  exponent_part = r"""([eE][-+]?[0-9]+)"""
+  fractional_constant = r"""([0-9]*\.[0-9]+)|([0-9]+\.)"""
+  floating_constant = \
+      '(((('+fractional_constant+')'+ \
+      exponent_part+'?)|([0-9]+'+exponent_part+')))'
+
+  # Ordinals
+  ordinal = r'@[0-9]+'
+  missing_ordinal_value = r'@'
+  # Don't allow ordinal values in octal (even invalid octal, like 09) or
+  # hexadecimal.
+  octal_or_hex_ordinal_disallowed = (
+      r'@((0[0-9]+)|(' + hex_prefix + hex_digits + '))')
+
+  ##
+  ## Rules for the normal state
+  ##
+  t_ignore = ' \t\r'
+
+  # Newlines
+  def t_NEWLINE(self, t):
+    r'\n+'
+    t.lexer.lineno += len(t.value)
+
+  # Operators
+  t_MINUS = r'-'
+  t_PLUS = r'\+'
+  t_QSTN = r'\?'
+
+  # =
+  t_EQUALS = r'='
+
+  # =>
+  t_RESPONSE = r'=>'
+
+  # Delimiters
+  t_LPAREN = r'\('
+  t_RPAREN = r'\)'
+  t_LBRACKET = r'\['
+  t_RBRACKET = r'\]'
+  t_LBRACE = r'\{'
+  t_RBRACE = r'\}'
+  t_LANGLE = r'<'
+  t_RANGLE = r'>'
+  t_COMMA = r','
+  t_DOT = r'\.'
+  t_SEMI = r';'
+
+  t_STRING_LITERAL = string_literal
+
+  # The following floating and integer constants are defined as
+  # functions to impose a strict order (otherwise, decimal
+  # is placed before the others because its regex is longer,
+  # and this is bad)
+  #
+  @TOKEN(floating_constant)
+  def t_FLOAT_CONST(self, t):
+    return t
+
+  @TOKEN(hex_constant)
+  def t_INT_CONST_HEX(self, t):
+    return t
+
+  @TOKEN(octal_constant_disallowed)
+  def t_OCTAL_CONSTANT_DISALLOWED(self, t):
+    msg = "Octal values not allowed"
+    self._error(msg, t)
+
+  @TOKEN(decimal_constant)
+  def t_INT_CONST_DEC(self, t):
+    return t
+
+  # unmatched string literals are caught by the preprocessor
+
+  @TOKEN(bad_string_literal)
+  def t_BAD_STRING_LITERAL(self, t):
+    msg = "String contains invalid escape code"
+    self._error(msg, t)
+
+  # Handle ordinal-related tokens in the right order:
+  @TOKEN(octal_or_hex_ordinal_disallowed)
+  def t_OCTAL_OR_HEX_ORDINAL_DISALLOWED(self, t):
+    msg = "Octal and hexadecimal ordinal values not allowed"
+    self._error(msg, t)
+
+  @TOKEN(ordinal)
+  def t_ORDINAL(self, t):
+    return t
+
+  @TOKEN(missing_ordinal_value)
+  def t_BAD_ORDINAL(self, t):
+    msg = "Missing ordinal value"
+    self._error(msg, t)
+
+  @TOKEN(identifier)
+  def t_NAME(self, t):
+    t.type = self.keyword_map.get(t.value, "NAME")
+    return t
+
+  # Ignore C and C++ style comments
+  def t_COMMENT(self, t):
+    r'(/\*(.|\n)*?\*/)|(//.*(\n[ \t]*//.*)*)'
+    t.lexer.lineno += t.value.count("\n")
+
+  def t_error(self, t):
+    msg = "Illegal character %s" % repr(t.value[0])
+    self._error(msg, t)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/lexer_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/lexer_unittest.py
new file mode 100644
index 00000000..bc9f8354
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/lexer_unittest.py
@@ -0,0 +1,194 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import importlib.util
+import os.path
+import sys
+import unittest
+
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = os.path.abspath(__file__)
+  while True:
+    path, tail = os.path.split(path)
+    assert tail
+    if tail == dirname:
+      return path
+
+sys.path.insert(1, os.path.join(_GetDirAbove("mojo"), "third_party"))
+from ply import lex
+
+try:
+  importlib.util.find_spec("mojom")
+except ImportError:
+  sys.path.append(os.path.join(_GetDirAbove("pylib"), "pylib"))
+import mojom.parse.lexer
+
+# This (monkey-patching LexToken to make comparison value-based) is evil, but
+# we'll do it anyway. (I'm pretty sure ply's lexer never cares about comparing
+# for object identity.)
+def _LexTokenEq(self, other):
+  return self.type == other.type and self.value == other.value and \
+         self.lineno == other.lineno and self.lexpos == other.lexpos
+
+
+setattr(lex.LexToken, '__eq__', _LexTokenEq)
+
+
+def _MakeLexToken(token_type, value, lineno=1, lexpos=0):
+  """Makes a LexToken with the given parameters. (Note that lineno is 1-based,
+  but lexpos is 0-based.)"""
+  rv = lex.LexToken()
+  rv.type, rv.value, rv.lineno, rv.lexpos = token_type, value, lineno, lexpos
+  return rv
+
+
+def _MakeLexTokenForKeyword(keyword, **kwargs):
+  """Makes a LexToken for the given keyword."""
+  return _MakeLexToken(keyword.upper(), keyword.lower(), **kwargs)
+
+
+class LexerTest(unittest.TestCase):
+  """Tests |mojom.parse.lexer.Lexer|."""
+
+  def __init__(self, *args, **kwargs):
+    unittest.TestCase.__init__(self, *args, **kwargs)
+    # Clone all lexer instances from this one, since making a lexer is slow.
+    self._zygote_lexer = lex.lex(mojom.parse.lexer.Lexer("my_file.mojom"))
+
+  def testValidKeywords(self):
+    """Tests valid keywords."""
+    self.assertEquals(
+        self._SingleTokenForInput("handle"), _MakeLexTokenForKeyword("handle"))
+    self.assertEquals(
+        self._SingleTokenForInput("import"), _MakeLexTokenForKeyword("import"))
+    self.assertEquals(
+        self._SingleTokenForInput("module"), _MakeLexTokenForKeyword("module"))
+    self.assertEquals(
+        self._SingleTokenForInput("struct"), _MakeLexTokenForKeyword("struct"))
+    self.assertEquals(
+        self._SingleTokenForInput("union"), _MakeLexTokenForKeyword("union"))
+    self.assertEquals(
+        self._SingleTokenForInput("interface"),
+        _MakeLexTokenForKeyword("interface"))
+    self.assertEquals(
+        self._SingleTokenForInput("enum"), _MakeLexTokenForKeyword("enum"))
+    self.assertEquals(
+        self._SingleTokenForInput("const"), _MakeLexTokenForKeyword("const"))
+    self.assertEquals(
+        self._SingleTokenForInput("true"), _MakeLexTokenForKeyword("true"))
+    self.assertEquals(
+        self._SingleTokenForInput("false"), _MakeLexTokenForKeyword("false"))
+    self.assertEquals(
+        self._SingleTokenForInput("default"),
+        _MakeLexTokenForKeyword("default"))
+    self.assertEquals(
+        self._SingleTokenForInput("array"), _MakeLexTokenForKeyword("array"))
+    self.assertEquals(
+        self._SingleTokenForInput("map"), _MakeLexTokenForKeyword("map"))
+    self.assertEquals(
+        self._SingleTokenForInput("associated"),
+        _MakeLexTokenForKeyword("associated"))
+
+  def testValidIdentifiers(self):
+    """Tests identifiers."""
+    self.assertEquals(
+        self._SingleTokenForInput("abcd"), _MakeLexToken("NAME", "abcd"))
+    self.assertEquals(
+        self._SingleTokenForInput("AbC_d012_"),
+        _MakeLexToken("NAME", "AbC_d012_"))
+    self.assertEquals(
+        self._SingleTokenForInput("_0123"), _MakeLexToken("NAME", "_0123"))
+
+  def testInvalidIdentifiers(self):
+    with self.assertRaisesRegexp(
+        mojom.parse.lexer.LexError,
+        r"^my_file\.mojom:1: Error: Illegal character '\$'$"):
+      self._TokensForInput("$abc")
+    with self.assertRaisesRegexp(
+        mojom.parse.lexer.LexError,
+        r"^my_file\.mojom:1: Error: Illegal character '\$'$"):
+      self._TokensForInput("a$bc")
+
+  def testDecimalIntegerConstants(self):
+    self.assertEquals(
+        self._SingleTokenForInput("0"), _MakeLexToken("INT_CONST_DEC", "0"))
+    self.assertEquals(
+        self._SingleTokenForInput("1"), _MakeLexToken("INT_CONST_DEC", "1"))
+    self.assertEquals(
+        self._SingleTokenForInput("123"), _MakeLexToken("INT_CONST_DEC", "123"))
+    self.assertEquals(
+        self._SingleTokenForInput("10"), _MakeLexToken("INT_CONST_DEC", "10"))
+
+  def testValidTokens(self):
+    """Tests valid tokens (which aren't tested elsewhere)."""
+    # Keywords tested in |testValidKeywords|.
+    # NAME tested in |testValidIdentifiers|.
+    self.assertEquals(
+        self._SingleTokenForInput("@123"), _MakeLexToken("ORDINAL", "@123"))
+    self.assertEquals(
+        self._SingleTokenForInput("456"), _MakeLexToken("INT_CONST_DEC", "456"))
+    self.assertEquals(
+        self._SingleTokenForInput("0x01aB2eF3"),
+        _MakeLexToken("INT_CONST_HEX", "0x01aB2eF3"))
+    self.assertEquals(
+        self._SingleTokenForInput("123.456"),
+        _MakeLexToken("FLOAT_CONST", "123.456"))
+    self.assertEquals(
+        self._SingleTokenForInput("\"hello\""),
+        _MakeLexToken("STRING_LITERAL", "\"hello\""))
+    self.assertEquals(
+        self._SingleTokenForInput("+"), _MakeLexToken("PLUS", "+"))
+    self.assertEquals(
+        self._SingleTokenForInput("-"), _MakeLexToken("MINUS", "-"))
+    self.assertEquals(
+        self._SingleTokenForInput("?"), _MakeLexToken("QSTN", "?"))
+    self.assertEquals(
+        self._SingleTokenForInput("="), _MakeLexToken("EQUALS", "="))
+    self.assertEquals(
+        self._SingleTokenForInput("=>"), _MakeLexToken("RESPONSE", "=>"))
+    self.assertEquals(
+        self._SingleTokenForInput("("), _MakeLexToken("LPAREN", "("))
+    self.assertEquals(
+        self._SingleTokenForInput(")"), _MakeLexToken("RPAREN", ")"))
+    self.assertEquals(
+        self._SingleTokenForInput("["), _MakeLexToken("LBRACKET", "["))
+    self.assertEquals(
+        self._SingleTokenForInput("]"), _MakeLexToken("RBRACKET", "]"))
+    self.assertEquals(
+        self._SingleTokenForInput("{"), _MakeLexToken("LBRACE", "{"))
+    self.assertEquals(
+        self._SingleTokenForInput("}"), _MakeLexToken("RBRACE", "}"))
+    self.assertEquals(
+        self._SingleTokenForInput("<"), _MakeLexToken("LANGLE", "<"))
+    self.assertEquals(
+        self._SingleTokenForInput(">"), _MakeLexToken("RANGLE", ">"))
+    self.assertEquals(
+        self._SingleTokenForInput(";"), _MakeLexToken("SEMI", ";"))
+    self.assertEquals(
+        self._SingleTokenForInput(","), _MakeLexToken("COMMA", ","))
+    self.assertEquals(self._SingleTokenForInput("."), _MakeLexToken("DOT", "."))
+
+  def _TokensForInput(self, input_string):
+    """Gets a list of tokens for the given input string."""
+    lexer = self._zygote_lexer.clone()
+    lexer.input(input_string)
+    rv = []
+    while True:
+      tok = lexer.token()
+      if not tok:
+        return rv
+      rv.append(tok)
+
+  def _SingleTokenForInput(self, input_string):
+    """Gets the single token for the given input string. (Raises an exception if
+    the input string does not result in exactly one token.)"""
+    toks = self._TokensForInput(input_string)
+    assert len(toks) == 1
+    return toks[0]
+
+
+if __name__ == "__main__":
+  unittest.main()
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/parser.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/parser.py
new file mode 100644
index 00000000..1dffd98b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/parser.py
@@ -0,0 +1,510 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Generates a syntax tree from a Mojo IDL file."""
+
+# Breaking parser stanzas is unhelpful so allow longer lines.
+# pylint: disable=line-too-long
+
+import os.path
+import sys
+
+from mojom import fileutil
+from mojom.error import Error
+from mojom.parse import ast
+from mojom.parse.lexer import Lexer
+
+fileutil.AddLocalRepoThirdPartyDirToModulePath()
+from ply import lex
+from ply import yacc
+
+_MAX_ORDINAL_VALUE = 0xffffffff
+_MAX_ARRAY_SIZE = 0xffffffff
+
+
+class ParseError(Error):
+  """Class for errors from the parser."""
+
+  def __init__(self, filename, message, lineno=None, snippet=None):
+    Error.__init__(
+        self,
+        filename,
+        message,
+        lineno=lineno,
+        addenda=([snippet] if snippet else None))
+
+
+# We have methods which look like they could be functions:
+# pylint: disable=R0201
+class Parser:
+  def __init__(self, lexer, source, filename):
+    self.tokens = lexer.tokens
+    self.source = source
+    self.filename = filename
+
+  # Names of functions
+  #
+  # In general, we name functions after the left-hand-side of the rule(s) that
+  # they handle. E.g., |p_foo_bar| for a rule |foo_bar : ...|.
+  #
+  # There may be multiple functions handling rules for the same left-hand-side;
+  # then we name the functions |p_foo_bar_N| (for left-hand-side |foo_bar|),
+  # where N is a number (numbered starting from 1). Note that using multiple
+  # functions is actually more efficient than having single functions handle
+  # multiple rules (and, e.g., distinguishing them by examining |len(p)|).
+  #
+  # It's also possible to have a function handling multiple rules with different
+  # left-hand-sides. We do not do this.
+  #
+  # See http://www.dabeaz.com/ply/ply.html#ply_nn25 for more details.
+
+  # TODO(vtl): Get rid of the braces in the module "statement". (Consider
+  # renaming "module" -> "package".) Then we'll be able to have a single rule
+  # for root (by making module "optional").
+  def p_root_1(self, p):
+    """root : """
+    p[0] = ast.Mojom(None, ast.ImportList(), [])
+
+  def p_root_2(self, p):
+    """root : root module"""
+    if p[1].module is not None:
+      raise ParseError(
+          self.filename,
+          "Multiple \"module\" statements not allowed:",
+          p[2].lineno,
+          snippet=self._GetSnippet(p[2].lineno))
+    if p[1].import_list.items or p[1].definition_list:
+      raise ParseError(
+          self.filename,
+          "\"module\" statements must precede imports and definitions:",
+          p[2].lineno,
+          snippet=self._GetSnippet(p[2].lineno))
+    p[0] = p[1]
+    p[0].module = p[2]
+
+  def p_root_3(self, p):
+    """root : root import"""
+    if p[1].definition_list:
+      raise ParseError(
+          self.filename,
+          "\"import\" statements must precede definitions:",
+          p[2].lineno,
+          snippet=self._GetSnippet(p[2].lineno))
+    p[0] = p[1]
+    p[0].import_list.Append(p[2])
+
+  def p_root_4(self, p):
+    """root : root definition"""
+    p[0] = p[1]
+    p[0].definition_list.append(p[2])
+
+  def p_import(self, p):
+    """import : attribute_section IMPORT STRING_LITERAL SEMI"""
+    # 'eval' the literal to strip the quotes.
+    # TODO(vtl): This eval is dubious. We should unquote/unescape ourselves.
+    p[0] = ast.Import(
+        p[1], eval(p[3]), filename=self.filename, lineno=p.lineno(2))
+
+  def p_module(self, p):
+    """module : attribute_section MODULE identifier_wrapped SEMI"""
+    p[0] = ast.Module(p[3], p[1], filename=self.filename, lineno=p.lineno(2))
+
+  def p_definition(self, p):
+    """definition : struct
+                  | union
+                  | interface
+                  | enum
+                  | const
+                  | feature"""
+    p[0] = p[1]
+
+  def p_attribute_section_1(self, p):
+    """attribute_section : """
+    p[0] = None
+
+  def p_attribute_section_2(self, p):
+    """attribute_section : LBRACKET attribute_list RBRACKET"""
+    p[0] = p[2]
+
+  def p_attribute_list_1(self, p):
+    """attribute_list : """
+    p[0] = ast.AttributeList()
+
+  def p_attribute_list_2(self, p):
+    """attribute_list : nonempty_attribute_list"""
+    p[0] = p[1]
+
+  def p_nonempty_attribute_list_1(self, p):
+    """nonempty_attribute_list : attribute"""
+    p[0] = ast.AttributeList(p[1])
+
+  def p_nonempty_attribute_list_2(self, p):
+    """nonempty_attribute_list : nonempty_attribute_list COMMA attribute"""
+    p[0] = p[1]
+    p[0].Append(p[3])
+
+  def p_attribute_1(self, p):
+    """attribute : name_wrapped EQUALS identifier_wrapped"""
+    p[0] = ast.Attribute(p[1],
+                         p[3][1],
+                         filename=self.filename,
+                         lineno=p.lineno(1))
+
+  def p_attribute_2(self, p):
+    """attribute : name_wrapped EQUALS evaled_literal
+                 | name_wrapped EQUALS name_wrapped"""
+    p[0] = ast.Attribute(p[1], p[3], filename=self.filename, lineno=p.lineno(1))
+
+  def p_attribute_3(self, p):
+    """attribute : name_wrapped"""
+    p[0] = ast.Attribute(p[1], True, filename=self.filename, lineno=p.lineno(1))
+
+  def p_evaled_literal(self, p):
+    """evaled_literal : literal"""
+    # 'eval' the literal to strip the quotes. Handle keywords "true" and "false"
+    # specially since they cannot directly be evaluated to python boolean
+    # values.
+    if p[1] == "true":
+      p[0] = True
+    elif p[1] == "false":
+      p[0] = False
+    else:
+      p[0] = eval(p[1])
+
+  def p_struct_1(self, p):
+    """struct : attribute_section STRUCT name_wrapped LBRACE struct_body RBRACE SEMI"""
+    p[0] = ast.Struct(p[3], p[1], p[5])
+
+  def p_struct_2(self, p):
+    """struct : attribute_section STRUCT name_wrapped SEMI"""
+    p[0] = ast.Struct(p[3], p[1], None)
+
+  def p_struct_body_1(self, p):
+    """struct_body : """
+    p[0] = ast.StructBody()
+
+  def p_struct_body_2(self, p):
+    """struct_body : struct_body const
+                   | struct_body enum
+                   | struct_body struct_field"""
+    p[0] = p[1]
+    p[0].Append(p[2])
+
+  def p_struct_field(self, p):
+    """struct_field : attribute_section typename name_wrapped ordinal default SEMI"""
+    p[0] = ast.StructField(p[3], p[1], p[4], p[2], p[5])
+
+  def p_feature(self, p):
+    """feature : attribute_section FEATURE NAME LBRACE feature_body RBRACE SEMI"""
+    p[0] = ast.Feature(p[3], p[1], p[5])
+
+  def p_feature_body_1(self, p):
+    """feature_body : """
+    p[0] = ast.FeatureBody()
+
+  def p_feature_body_2(self, p):
+    """feature_body : feature_body const"""
+    p[0] = p[1]
+    p[0].Append(p[2])
+
+  def p_union(self, p):
+    """union : attribute_section UNION name_wrapped LBRACE union_body RBRACE SEMI"""
+    p[0] = ast.Union(p[3], p[1], p[5])
+
+  def p_union_body_1(self, p):
+    """union_body : """
+    p[0] = ast.UnionBody()
+
+  def p_union_body_2(self, p):
+    """union_body : union_body union_field"""
+    p[0] = p[1]
+    p[1].Append(p[2])
+
+  def p_union_field(self, p):
+    """union_field : attribute_section typename name_wrapped ordinal SEMI"""
+    p[0] = ast.UnionField(p[3], p[1], p[4], p[2])
+
+  def p_default_1(self, p):
+    """default : """
+    p[0] = None
+
+  def p_default_2(self, p):
+    """default : EQUALS constant"""
+    p[0] = p[2]
+
+  def p_interface(self, p):
+    """interface : attribute_section INTERFACE name_wrapped LBRACE interface_body RBRACE SEMI"""
+    p[0] = ast.Interface(p[3], p[1], p[5])
+
+  def p_interface_body_1(self, p):
+    """interface_body : """
+    p[0] = ast.InterfaceBody()
+
+  def p_interface_body_2(self, p):
+    """interface_body : interface_body const
+                      | interface_body enum
+                      | interface_body method"""
+    p[0] = p[1]
+    p[0].Append(p[2])
+
+  def p_response_1(self, p):
+    """response : """
+    p[0] = None
+
+  def p_response_2(self, p):
+    """response : RESPONSE LPAREN parameter_list RPAREN"""
+    p[0] = p[3]
+
+  def p_method(self, p):
+    """method : attribute_section name_wrapped ordinal LPAREN parameter_list RPAREN response SEMI"""
+    p[0] = ast.Method(p[2], p[1], p[3], p[5], p[7])
+
+  def p_parameter_list_1(self, p):
+    """parameter_list : """
+    p[0] = ast.ParameterList()
+
+  def p_parameter_list_2(self, p):
+    """parameter_list : nonempty_parameter_list"""
+    p[0] = p[1]
+
+  def p_nonempty_parameter_list_1(self, p):
+    """nonempty_parameter_list : parameter"""
+    p[0] = ast.ParameterList(p[1])
+
+  def p_nonempty_parameter_list_2(self, p):
+    """nonempty_parameter_list : nonempty_parameter_list COMMA parameter"""
+    p[0] = p[1]
+    p[0].Append(p[3])
+
+  def p_parameter(self, p):
+    """parameter : attribute_section typename name_wrapped ordinal"""
+    p[0] = ast.Parameter(
+        p[3], p[1], p[4], p[2], filename=self.filename, lineno=p.lineno(3))
+
+  def p_typename(self, p):
+    """typename : nonnullable_typename QSTN
+                | nonnullable_typename"""
+    if len(p) == 2:
+      p[0] = p[1]
+    else:
+      p[0] = p[1] + "?"
+
+  def p_nonnullable_typename(self, p):
+    """nonnullable_typename : basictypename
+                            | array
+                            | fixed_array
+                            | associative_array"""
+    p[0] = p[1]
+
+  def p_basictypename(self, p):
+    """basictypename : remotetype
+                     | receivertype
+                     | associatedremotetype
+                     | associatedreceivertype
+                     | identifier
+                     | ASSOCIATED identifier
+                     | handletype"""
+    if len(p) == 2:
+      p[0] = p[1]
+    else:
+      p[0] = "asso<" + p[2] + ">"
+
+  def p_remotetype(self, p):
+    """remotetype : PENDING_REMOTE LANGLE identifier RANGLE"""
+    p[0] = "rmt<%s>" % p[3]
+
+  def p_receivertype(self, p):
+    """receivertype : PENDING_RECEIVER LANGLE identifier RANGLE"""
+    p[0] = "rcv<%s>" % p[3]
+
+  def p_associatedremotetype(self, p):
+    """associatedremotetype : PENDING_ASSOCIATED_REMOTE LANGLE identifier RANGLE"""
+    p[0] = "rma<%s>" % p[3]
+
+  def p_associatedreceivertype(self, p):
+    """associatedreceivertype : PENDING_ASSOCIATED_RECEIVER LANGLE identifier RANGLE"""
+    p[0] = "rca<%s>" % p[3]
+
+  def p_handletype(self, p):
+    """handletype : HANDLE
+                  | HANDLE LANGLE name_wrapped RANGLE"""
+    if len(p) == 2:
+      p[0] = p[1]
+    else:
+      if p[3] not in ('data_pipe_consumer', 'data_pipe_producer',
+                      'message_pipe', 'shared_buffer', 'platform'):
+        # Note: We don't enable tracking of line numbers for everything, so we
+        # can't use |p.lineno(3)|.
+        raise ParseError(
+            self.filename,
+            "Invalid handle type %r:" % p[3],
+            lineno=p.lineno(1),
+            snippet=self._GetSnippet(p.lineno(1)))
+      p[0] = "handle<" + p[3] + ">"
+
+  def p_array(self, p):
+    """array : ARRAY LANGLE typename RANGLE"""
+    p[0] = p[3] + "[]"
+
+  def p_fixed_array(self, p):
+    """fixed_array : ARRAY LANGLE typename COMMA INT_CONST_DEC RANGLE"""
+    value = int(p[5])
+    if value == 0 or value > _MAX_ARRAY_SIZE:
+      raise ParseError(
+          self.filename,
+          "Fixed array size %d invalid:" % value,
+          lineno=p.lineno(5),
+          snippet=self._GetSnippet(p.lineno(5)))
+    p[0] = p[3] + "[" + p[5] + "]"
+
+  def p_associative_array(self, p):
+    """associative_array : MAP LANGLE identifier COMMA typename RANGLE"""
+    p[0] = p[5] + "{" + p[3] + "}"
+
+  def p_ordinal_1(self, p):
+    """ordinal : """
+    p[0] = None
+
+  def p_ordinal_2(self, p):
+    """ordinal : ORDINAL"""
+    value = int(p[1][1:])
+    if value > _MAX_ORDINAL_VALUE:
+      raise ParseError(
+          self.filename,
+          "Ordinal value %d too large:" % value,
+          lineno=p.lineno(1),
+          snippet=self._GetSnippet(p.lineno(1)))
+    p[0] = ast.Ordinal(value, filename=self.filename, lineno=p.lineno(1))
+
+  def p_enum_1(self, p):
+    """enum : attribute_section ENUM name_wrapped LBRACE enum_value_list RBRACE SEMI
+            | attribute_section ENUM name_wrapped LBRACE \
+                    nonempty_enum_value_list COMMA RBRACE SEMI"""
+    p[0] = ast.Enum(
+        p[3], p[1], p[5], filename=self.filename, lineno=p.lineno(2))
+
+  def p_enum_2(self, p):
+    """enum : attribute_section ENUM name_wrapped SEMI"""
+    p[0] = ast.Enum(
+        p[3], p[1], None, filename=self.filename, lineno=p.lineno(2))
+
+  def p_enum_value_list_1(self, p):
+    """enum_value_list : """
+    p[0] = ast.EnumValueList()
+
+  def p_enum_value_list_2(self, p):
+    """enum_value_list : nonempty_enum_value_list"""
+    p[0] = p[1]
+
+  def p_nonempty_enum_value_list_1(self, p):
+    """nonempty_enum_value_list : enum_value"""
+    p[0] = ast.EnumValueList(p[1])
+
+  def p_nonempty_enum_value_list_2(self, p):
+    """nonempty_enum_value_list : nonempty_enum_value_list COMMA enum_value"""
+    p[0] = p[1]
+    p[0].Append(p[3])
+
+  def p_enum_value(self, p):
+    """enum_value : attribute_section name_wrapped
+                  | attribute_section name_wrapped EQUALS int
+                  | attribute_section name_wrapped EQUALS identifier_wrapped"""
+    p[0] = ast.EnumValue(
+        p[2],
+        p[1],
+        p[4] if len(p) == 5 else None,
+        filename=self.filename,
+        lineno=p.lineno(2))
+
+  def p_const(self, p):
+    """const : attribute_section CONST typename name_wrapped EQUALS constant SEMI"""
+    p[0] = ast.Const(p[4], p[1], p[3], p[6])
+
+  def p_constant(self, p):
+    """constant : literal
+                | identifier_wrapped"""
+    p[0] = p[1]
+
+  def p_identifier_wrapped(self, p):
+    """identifier_wrapped : identifier"""
+    p[0] = ('IDENTIFIER', p[1])
+
+  # TODO(vtl): Make this produce a "wrapped" identifier (probably as an
+  # |ast.Identifier|, to be added) and get rid of identifier_wrapped.
+  def p_identifier(self, p):
+    """identifier : name_wrapped
+                  | name_wrapped DOT identifier"""
+    p[0] = ''.join(p[1:])
+
+  # Allow 'feature' to be a name literal not just a keyword.
+  def p_name_wrapped(self, p):
+    """name_wrapped : NAME
+                    | FEATURE"""
+    p[0] = p[1]
+
+  def p_literal(self, p):
+    """literal : int
+               | float
+               | TRUE
+               | FALSE
+               | DEFAULT
+               | STRING_LITERAL"""
+    p[0] = p[1]
+
+  def p_int(self, p):
+    """int : int_const
+           | PLUS int_const
+           | MINUS int_const"""
+    p[0] = ''.join(p[1:])
+
+  def p_int_const(self, p):
+    """int_const : INT_CONST_DEC
+                 | INT_CONST_HEX"""
+    p[0] = p[1]
+
+  def p_float(self, p):
+    """float : FLOAT_CONST
+             | PLUS FLOAT_CONST
+             | MINUS FLOAT_CONST"""
+    p[0] = ''.join(p[1:])
+
+  def p_error(self, e):
+    if e is None:
+      # Unexpected EOF.
+      # TODO(vtl): Can we figure out what's missing?
+      raise ParseError(self.filename, "Unexpected end of file")
+
+    if e.value == 'feature':
+      raise ParseError(self.filename,
+                       "`feature` is reserved for a future mojom keyword",
+                       lineno=e.lineno,
+                       snippet=self._GetSnippet(e.lineno))
+
+    raise ParseError(
+        self.filename,
+        "Unexpected %r:" % e.value,
+        lineno=e.lineno,
+        snippet=self._GetSnippet(e.lineno))
+
+  def _GetSnippet(self, lineno):
+    return self.source.split('\n')[lineno - 1]
+
+
+def Parse(source, filename):
+  """Parse source file to AST.
+
+  Args:
+    source: The source text as a str (Python 2 or 3) or unicode (Python 2).
+    filename: The filename that |source| originates from.
+
+  Returns:
+    The AST as a mojom.parse.ast.Mojom object.
+  """
+  lexer = Lexer(filename)
+  parser = Parser(lexer, source, filename)
+
+  lex.lex(object=lexer)
+  yacc.yacc(module=parser, debug=0, write_tables=0)
+
+  tree = yacc.parse(source)
+  return tree
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/parser_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/parser_unittest.py
new file mode 100644
index 00000000..0a26307b
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom/parse/parser_unittest.py
@@ -0,0 +1,1375 @@
+# Copyright 2014 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+from mojom.parse import ast
+from mojom.parse import lexer
+from mojom.parse import parser
+
+class ParserTest(unittest.TestCase):
+  """Tests |parser.Parse()|."""
+
+  def testTrivialValidSource(self):
+    """Tests a trivial, but valid, .mojom source."""
+
+    source = """\
+        // This is a comment.
+
+        module my_module;
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testSourceWithCrLfs(self):
+    """Tests a .mojom source with CR-LFs instead of LFs."""
+
+    source = "// This is a comment.\r\n\r\nmodule my_module;\r\n"
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testUnexpectedEOF(self):
+    """Tests a "truncated" .mojom source."""
+
+    source = """\
+        // This is a comment.
+
+        module my_module
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom: Error: Unexpected end of file$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testCommentLineNumbers(self):
+    """Tests that line numbers are correctly tracked when comments are
+    present."""
+
+    source1 = """\
+        // Isolated C++-style comments.
+
+        // Foo.
+        asdf1
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:4: Error: Unexpected 'asdf1':\n *asdf1$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        // Consecutive C++-style comments.
+        // Foo.
+        // Bar.
+
+        struct Yada {  // Baz.
+                       // Quux.
+          int32 x;
+        };
+
+        asdf2
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:10: Error: Unexpected 'asdf2':\n *asdf2$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        /* Single-line C-style comments. */
+        /* Foobar. */
+
+        /* Baz. */
+        asdf3
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:5: Error: Unexpected 'asdf3':\n *asdf3$"):
+      parser.Parse(source3, "my_file.mojom")
+
+    source4 = """\
+        /* Multi-line C-style comments.
+        */
+        /*
+        Foo.
+        Bar.
+        */
+
+        /* Baz
+           Quux. */
+        asdf4
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:10: Error: Unexpected 'asdf4':\n *asdf4$"):
+      parser.Parse(source4, "my_file.mojom")
+
+  def testSimpleStruct(self):
+    """Tests a simple .mojom source that just defines a struct."""
+
+    source = """\
+        module my_module;
+
+        struct MyStruct {
+          int32 a;
+          double b;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Struct(
+                'MyStruct', None,
+                ast.StructBody([
+                    ast.StructField('a', None, None, 'int32', None),
+                    ast.StructField('b', None, None, 'double', None)
+                ]))
+        ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testSimpleStructWithoutModule(self):
+    """Tests a simple struct without an explict module statement."""
+
+    source = """\
+        struct MyStruct {
+          int32 a;
+          double b;
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.StructField('a', None, None, 'int32', None),
+                ast.StructField('b', None, None, 'double', None)
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testValidStructDefinitions(self):
+    """Tests all types of definitions that can occur in a struct."""
+
+    source = """\
+        struct MyStruct {
+          enum MyEnum { VALUE };
+          const double kMyConst = 1.23;
+          int32 a;
+          SomeOtherStruct b;  // Invalidity detected at another stage.
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.Enum('MyEnum', None,
+                         ast.EnumValueList(ast.EnumValue('VALUE', None, None))),
+                ast.Const('kMyConst', None, 'double', '1.23'),
+                ast.StructField('a', None, None, 'int32', None),
+                ast.StructField('b', None, None, 'SomeOtherStruct', None)
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidStructDefinitions(self):
+    """Tests that definitions that aren't allowed in a struct are correctly
+    detected."""
+
+    source1 = """\
+        struct MyStruct {
+          MyMethod(int32 a);
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected '\(':\n"
+        r" *MyMethod\(int32 a\);$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        struct MyStruct {
+          struct MyInnerStruct {
+            int32 a;
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'struct':\n"
+        r" *struct MyInnerStruct {$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        struct MyStruct {
+          interface MyInterface {
+            MyMethod(int32 a);
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Unexpected 'interface':\n"
+        r" *interface MyInterface {$"):
+      parser.Parse(source3, "my_file.mojom")
+
+  def testMissingModuleName(self):
+    """Tests an (invalid) .mojom with a missing module name."""
+
+    source1 = """\
+        // Missing module name.
+        module ;
+        struct MyStruct {
+          int32 a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Unexpected ';':\n *module ;$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    # Another similar case, but make sure that line-number tracking/reporting
+    # is correct.
+    source2 = """\
+        module
+        // This line intentionally left unblank.
+
+        struct MyStruct {
+          int32 a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:4: Error: Unexpected 'struct':\n"
+        r" *struct MyStruct {$"):
+      parser.Parse(source2, "my_file.mojom")
+
+  def testMultipleModuleStatements(self):
+    """Tests an (invalid) .mojom with multiple module statements."""
+
+    source = """\
+        module foo;
+        module bar;
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Multiple \"module\" statements not "
+        r"allowed:\n *module bar;$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testModuleStatementAfterImport(self):
+    """Tests an (invalid) .mojom with a module statement after an import."""
+
+    source = """\
+        import "foo.mojom";
+        module foo;
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: \"module\" statements must precede imports "
+        r"and definitions:\n *module foo;$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testModuleStatementAfterDefinition(self):
+    """Tests an (invalid) .mojom with a module statement after a definition."""
+
+    source = """\
+        struct MyStruct {
+          int32 a;
+        };
+        module foo;
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:4: Error: \"module\" statements must precede imports "
+        r"and definitions:\n *module foo;$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testImportStatementAfterDefinition(self):
+    """Tests an (invalid) .mojom with an import statement after a definition."""
+
+    source = """\
+        struct MyStruct {
+          int32 a;
+        };
+        import "foo.mojom";
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:4: Error: \"import\" statements must precede "
+        r"definitions:\n *import \"foo.mojom\";$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testEnums(self):
+    """Tests that enum statements are correctly parsed."""
+
+    source = """\
+        module my_module;
+        enum MyEnum1 { VALUE1, VALUE2 };  // No trailing comma.
+        enum MyEnum2 {
+          VALUE1 = -1,
+          VALUE2 = 0,
+          VALUE3 = + 987,  // Check that space is allowed.
+          VALUE4 = 0xAF12,
+          VALUE5 = -0x09bcd,
+          VALUE6 = VALUE5,
+          VALUE7,  // Leave trailing comma.
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Enum(
+                'MyEnum1', None,
+                ast.EnumValueList([
+                    ast.EnumValue('VALUE1', None, None),
+                    ast.EnumValue('VALUE2', None, None)
+                ])),
+            ast.Enum(
+                'MyEnum2', None,
+                ast.EnumValueList([
+                    ast.EnumValue('VALUE1', None, '-1'),
+                    ast.EnumValue('VALUE2', None, '0'),
+                    ast.EnumValue('VALUE3', None, '+987'),
+                    ast.EnumValue('VALUE4', None, '0xAF12'),
+                    ast.EnumValue('VALUE5', None, '-0x09bcd'),
+                    ast.EnumValue('VALUE6', None, ('IDENTIFIER', 'VALUE5')),
+                    ast.EnumValue('VALUE7', None, None)
+                ]))
+        ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidEnumInitializers(self):
+    """Tests that invalid enum initializers are correctly detected."""
+
+    # Floating point value.
+    source2 = "enum MyEnum { VALUE = 0.123 };"
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:1: Error: Unexpected '0\.123':\n"
+        r"enum MyEnum { VALUE = 0\.123 };$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    # Boolean value.
+    source2 = "enum MyEnum { VALUE = true };"
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:1: Error: Unexpected 'true':\n"
+        r"enum MyEnum { VALUE = true };$"):
+      parser.Parse(source2, "my_file.mojom")
+
+  def testConsts(self):
+    """Tests some constants and struct members initialized with them."""
+
+    source = """\
+        module my_module;
+
+        struct MyStruct {
+          const int8 kNumber = -1;
+          int8 number@0 = kNumber;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Struct(
+                'MyStruct', None,
+                ast.StructBody([
+                    ast.Const('kNumber', None, 'int8', '-1'),
+                    ast.StructField('number', None, ast.Ordinal(0), 'int8',
+                                    ('IDENTIFIER', 'kNumber'))
+                ]))
+        ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testNoConditionals(self):
+    """Tests that ?: is not allowed."""
+
+    source = """\
+        module my_module;
+
+        enum MyEnum {
+          MY_ENUM_1 = 1 ? 2 : 3
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:4: Error: Unexpected '\?':\n"
+        r" *MY_ENUM_1 = 1 \? 2 : 3$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testSimpleOrdinals(self):
+    """Tests that (valid) ordinal values are scanned correctly."""
+
+    source = """\
+        module my_module;
+
+        // This isn't actually valid .mojom, but the problem (missing ordinals)
+        // should be handled at a different level.
+        struct MyStruct {
+          int32 a0@0;
+          int32 a1@1;
+          int32 a2@2;
+          int32 a9@9;
+          int32 a10 @10;
+          int32 a11 @11;
+          int32 a29 @29;
+          int32 a1234567890 @1234567890;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Struct(
+                'MyStruct', None,
+                ast.StructBody([
+                    ast.StructField('a0', None, ast.Ordinal(0), 'int32', None),
+                    ast.StructField('a1', None, ast.Ordinal(1), 'int32', None),
+                    ast.StructField('a2', None, ast.Ordinal(2), 'int32', None),
+                    ast.StructField('a9', None, ast.Ordinal(9), 'int32', None),
+                    ast.StructField('a10', None, ast.Ordinal(10), 'int32',
+                                    None),
+                    ast.StructField('a11', None, ast.Ordinal(11), 'int32',
+                                    None),
+                    ast.StructField('a29', None, ast.Ordinal(29), 'int32',
+                                    None),
+                    ast.StructField('a1234567890', None,
+                                    ast.Ordinal(1234567890), 'int32', None)
+                ]))
+        ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidOrdinals(self):
+    """Tests that (lexically) invalid ordinals are correctly detected."""
+
+    source1 = """\
+        module my_module;
+
+        struct MyStruct {
+          int32 a_missing@;
+        };
+        """
+    with self.assertRaisesRegexp(
+        lexer.LexError, r"^my_file\.mojom:4: Error: Missing ordinal value$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        module my_module;
+
+        struct MyStruct {
+          int32 a_octal@01;
+        };
+        """
+    with self.assertRaisesRegexp(
+        lexer.LexError, r"^my_file\.mojom:4: Error: "
+        r"Octal and hexadecimal ordinal values not allowed$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        module my_module; struct MyStruct { int32 a_invalid_octal@08; };
+        """
+    with self.assertRaisesRegexp(
+        lexer.LexError, r"^my_file\.mojom:1: Error: "
+        r"Octal and hexadecimal ordinal values not allowed$"):
+      parser.Parse(source3, "my_file.mojom")
+
+    source4 = "module my_module; struct MyStruct { int32 a_hex@0x1aB9; };"
+    with self.assertRaisesRegexp(
+        lexer.LexError, r"^my_file\.mojom:1: Error: "
+        r"Octal and hexadecimal ordinal values not allowed$"):
+      parser.Parse(source4, "my_file.mojom")
+
+    source5 = "module my_module; struct MyStruct { int32 a_hex@0X0; };"
+    with self.assertRaisesRegexp(
+        lexer.LexError, r"^my_file\.mojom:1: Error: "
+        r"Octal and hexadecimal ordinal values not allowed$"):
+      parser.Parse(source5, "my_file.mojom")
+
+    source6 = """\
+        struct MyStruct {
+          int32 a_too_big@999999999999;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: "
+        r"Ordinal value 999999999999 too large:\n"
+        r" *int32 a_too_big@999999999999;$"):
+      parser.Parse(source6, "my_file.mojom")
+
+  def testNestedNamespace(self):
+    """Tests that "nested" namespaces work."""
+
+    source = """\
+        module my.mod;
+
+        struct MyStruct {
+          int32 a;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my.mod'), None), ast.ImportList(), [
+            ast.Struct(
+                'MyStruct', None,
+                ast.StructBody(ast.StructField('a', None, None, 'int32', None)))
+        ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testValidHandleTypes(self):
+    """Tests (valid) handle types."""
+
+    source = """\
+        struct MyStruct {
+          handle a;
+          handle<data_pipe_consumer> b;
+          handle <data_pipe_producer> c;
+          handle < message_pipe > d;
+          handle
+            < shared_buffer
+            > e;
+          handle
+            <platform
+
+            > f;
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.StructField('a', None, None, 'handle', None),
+                ast.StructField('b', None, None, 'handle<data_pipe_consumer>',
+                                None),
+                ast.StructField('c', None, None, 'handle<data_pipe_producer>',
+                                None),
+                ast.StructField('d', None, None, 'handle<message_pipe>', None),
+                ast.StructField('e', None, None, 'handle<shared_buffer>', None),
+                ast.StructField('f', None, None, 'handle<platform>', None)
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidHandleType(self):
+    """Tests an invalid (unknown) handle type."""
+
+    source = """\
+        struct MyStruct {
+          handle<wtf_is_this> foo;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: "
+        r"Invalid handle type 'wtf_is_this':\n"
+        r" *handle<wtf_is_this> foo;$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testValidDefaultValues(self):
+    """Tests default values that are valid (to the parser)."""
+
+    source = """\
+        struct MyStruct {
+          int16 a0 = 0;
+          uint16 a1 = 0x0;
+          uint16 a2 = 0x00;
+          uint16 a3 = 0x01;
+          uint16 a4 = 0xcd;
+          int32 a5 = 12345;
+          int64 a6 = -12345;
+          int64 a7 = +12345;
+          uint32 a8 = 0x12cd3;
+          uint32 a9 = -0x12cD3;
+          uint32 a10 = +0x12CD3;
+          bool a11 = true;
+          bool a12 = false;
+          float a13 = 1.2345;
+          float a14 = -1.2345;
+          float a15 = +1.2345;
+          float a16 = 123.;
+          float a17 = .123;
+          double a18 = 1.23E10;
+          double a19 = 1.E-10;
+          double a20 = .5E+10;
+          double a21 = -1.23E10;
+          double a22 = +.123E10;
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.StructField('a0', None, None, 'int16', '0'),
+                ast.StructField('a1', None, None, 'uint16', '0x0'),
+                ast.StructField('a2', None, None, 'uint16', '0x00'),
+                ast.StructField('a3', None, None, 'uint16', '0x01'),
+                ast.StructField('a4', None, None, 'uint16', '0xcd'),
+                ast.StructField('a5', None, None, 'int32', '12345'),
+                ast.StructField('a6', None, None, 'int64', '-12345'),
+                ast.StructField('a7', None, None, 'int64', '+12345'),
+                ast.StructField('a8', None, None, 'uint32', '0x12cd3'),
+                ast.StructField('a9', None, None, 'uint32', '-0x12cD3'),
+                ast.StructField('a10', None, None, 'uint32', '+0x12CD3'),
+                ast.StructField('a11', None, None, 'bool', 'true'),
+                ast.StructField('a12', None, None, 'bool', 'false'),
+                ast.StructField('a13', None, None, 'float', '1.2345'),
+                ast.StructField('a14', None, None, 'float', '-1.2345'),
+                ast.StructField('a15', None, None, 'float', '+1.2345'),
+                ast.StructField('a16', None, None, 'float', '123.'),
+                ast.StructField('a17', None, None, 'float', '.123'),
+                ast.StructField('a18', None, None, 'double', '1.23E10'),
+                ast.StructField('a19', None, None, 'double', '1.E-10'),
+                ast.StructField('a20', None, None, 'double', '.5E+10'),
+                ast.StructField('a21', None, None, 'double', '-1.23E10'),
+                ast.StructField('a22', None, None, 'double', '+.123E10')
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testValidFixedSizeArray(self):
+    """Tests parsing a fixed size array."""
+
+    source = """\
+        struct MyStruct {
+          array<int32> normal_array;
+          array<int32, 1> fixed_size_array_one_entry;
+          array<int32, 10> fixed_size_array_ten_entries;
+          array<array<array<int32, 1>>, 2> nested_arrays;
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.StructField('normal_array', None, None, 'int32[]', None),
+                ast.StructField('fixed_size_array_one_entry', None, None,
+                                'int32[1]', None),
+                ast.StructField('fixed_size_array_ten_entries', None, None,
+                                'int32[10]', None),
+                ast.StructField('nested_arrays', None, None, 'int32[1][][2]',
+                                None)
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testValidNestedArray(self):
+    """Tests parsing a nested array."""
+
+    source = "struct MyStruct { array<array<int32>> nested_array; };"
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody(
+                ast.StructField('nested_array', None, None, 'int32[][]', None)))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidFixedArraySize(self):
+    """Tests that invalid fixed array bounds are correctly detected."""
+
+    source1 = """\
+        struct MyStruct {
+          array<int32, 0> zero_size_array;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Fixed array size 0 invalid:\n"
+        r" *array<int32, 0> zero_size_array;$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        struct MyStruct {
+          array<int32, 999999999999> too_big_array;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Fixed array size 999999999999 invalid:\n"
+        r" *array<int32, 999999999999> too_big_array;$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        struct MyStruct {
+          array<int32, abcdefg> not_a_number;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'abcdefg':\n"
+        r" *array<int32, abcdefg> not_a_number;"):
+      parser.Parse(source3, "my_file.mojom")
+
+  def testValidAssociativeArrays(self):
+    """Tests that we can parse valid associative array structures."""
+
+    source1 = "struct MyStruct { map<string, uint8> data; };"
+    expected1 = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody(
+                [ast.StructField('data', None, None, 'uint8{string}', None)]))
+    ])
+    self.assertEquals(parser.Parse(source1, "my_file.mojom"), expected1)
+
+    source2 = "interface MyInterface { MyMethod(map<string, uint8> a); };"
+    expected2 = ast.Mojom(None, ast.ImportList(), [
+        ast.Interface(
+            'MyInterface', None,
+            ast.InterfaceBody(
+                ast.Method(
+                    'MyMethod', None, None,
+                    ast.ParameterList(
+                        ast.Parameter('a', None, None, 'uint8{string}')),
+                    None)))
+    ])
+    self.assertEquals(parser.Parse(source2, "my_file.mojom"), expected2)
+
+    source3 = "struct MyStruct { map<string, array<uint8>> data; };"
+    expected3 = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody(
+                [ast.StructField('data', None, None, 'uint8[]{string}', None)]))
+    ])
+    self.assertEquals(parser.Parse(source3, "my_file.mojom"), expected3)
+
+  def testValidMethod(self):
+    """Tests parsing method declarations."""
+
+    source1 = "interface MyInterface { MyMethod(int32 a); };"
+    expected1 = ast.Mojom(None, ast.ImportList(), [
+        ast.Interface(
+            'MyInterface', None,
+            ast.InterfaceBody(
+                ast.Method(
+                    'MyMethod', None, None,
+                    ast.ParameterList(ast.Parameter('a', None, None, 'int32')),
+                    None)))
+    ])
+    self.assertEquals(parser.Parse(source1, "my_file.mojom"), expected1)
+
+    source2 = """\
+        interface MyInterface {
+          MyMethod1@0(int32 a@0, int64 b@1);
+          MyMethod2@1() => ();
+        };
+        """
+    expected2 = ast.Mojom(None, ast.ImportList(), [
+        ast.Interface(
+            'MyInterface', None,
+            ast.InterfaceBody([
+                ast.Method(
+                    'MyMethod1', None, ast.Ordinal(0),
+                    ast.ParameterList([
+                        ast.Parameter('a', None, ast.Ordinal(0), 'int32'),
+                        ast.Parameter('b', None, ast.Ordinal(1), 'int64')
+                    ]), None),
+                ast.Method('MyMethod2', None, ast.Ordinal(1),
+                           ast.ParameterList(), ast.ParameterList())
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source2, "my_file.mojom"), expected2)
+
+    source3 = """\
+        interface MyInterface {
+          MyMethod(string a) => (int32 a, bool b);
+        };
+        """
+    expected3 = ast.Mojom(None, ast.ImportList(), [
+        ast.Interface(
+            'MyInterface', None,
+            ast.InterfaceBody(
+                ast.Method(
+                    'MyMethod', None, None,
+                    ast.ParameterList(ast.Parameter('a', None, None, 'string')),
+                    ast.ParameterList([
+                        ast.Parameter('a', None, None, 'int32'),
+                        ast.Parameter('b', None, None, 'bool')
+                    ]))))
+    ])
+    self.assertEquals(parser.Parse(source3, "my_file.mojom"), expected3)
+
+  def testInvalidMethods(self):
+    """Tests that invalid method declarations are correctly detected."""
+
+    # No trailing commas.
+    source1 = """\
+        interface MyInterface {
+          MyMethod(string a,);
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected '\)':\n"
+        r" *MyMethod\(string a,\);$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    # No leading commas.
+    source2 = """\
+        interface MyInterface {
+          MyMethod(, string a);
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected ',':\n"
+        r" *MyMethod\(, string a\);$"):
+      parser.Parse(source2, "my_file.mojom")
+
+  def testValidInterfaceDefinitions(self):
+    """Tests all types of definitions that can occur in an interface."""
+
+    source = """\
+        interface MyInterface {
+          enum MyEnum { VALUE };
+          const int32 kMyConst = 123;
+          MyMethod(int32 x) => (MyEnum y);
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Interface(
+            'MyInterface', None,
+            ast.InterfaceBody([
+                ast.Enum('MyEnum', None,
+                         ast.EnumValueList(ast.EnumValue('VALUE', None, None))),
+                ast.Const('kMyConst', None, 'int32', '123'),
+                ast.Method(
+                    'MyMethod', None, None,
+                    ast.ParameterList(ast.Parameter('x', None, None, 'int32')),
+                    ast.ParameterList(ast.Parameter('y', None, None, 'MyEnum')))
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidInterfaceDefinitions(self):
+    """Tests that definitions that aren't allowed in an interface are correctly
+    detected."""
+
+    source1 = """\
+        interface MyInterface {
+          struct MyStruct {
+            int32 a;
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'struct':\n"
+        r" *struct MyStruct {$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        interface MyInterface {
+          interface MyInnerInterface {
+            MyMethod(int32 x);
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Unexpected 'interface':\n"
+        r" *interface MyInnerInterface {$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        interface MyInterface {
+          int32 my_field;
+        };
+        """
+    # The parser thinks that "int32" is a plausible name for a method, so it's
+    # "my_field" that gives it away.
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'my_field':\n"
+        r" *int32 my_field;$"):
+      parser.Parse(source3, "my_file.mojom")
+
+  def testValidAttributes(self):
+    """Tests parsing attributes (and attribute lists)."""
+
+    # Note: We use structs because they have (optional) attribute lists.
+
+    # Empty attribute list.
+    source1 = "[] struct MyStruct {};"
+    expected1 = ast.Mojom(
+        None, ast.ImportList(),
+        [ast.Struct('MyStruct', ast.AttributeList(), ast.StructBody())])
+    self.assertEquals(parser.Parse(source1, "my_file.mojom"), expected1)
+
+    # One-element attribute list, with name value.
+    source2 = "[MyAttribute=MyName] struct MyStruct {};"
+    expected2 = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct('MyStruct',
+                   ast.AttributeList(ast.Attribute("MyAttribute", "MyName")),
+                   ast.StructBody())
+    ])
+    self.assertEquals(parser.Parse(source2, "my_file.mojom"), expected2)
+
+    # Two-element attribute list, with one string value and one integer value.
+    source3 = "[MyAttribute1 = \"hello\", MyAttribute2 = 5] struct MyStruct {};"
+    expected3 = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct',
+            ast.AttributeList([
+                ast.Attribute("MyAttribute1", "hello"),
+                ast.Attribute("MyAttribute2", 5)
+            ]), ast.StructBody())
+    ])
+    self.assertEquals(parser.Parse(source3, "my_file.mojom"), expected3)
+
+    # Various places that attribute list is allowed.
+    source4 = """\
+        [Attr0=0] module my_module;
+
+        [Attr1=1] import "my_import";
+
+        [Attr2=2] struct MyStruct {
+          [Attr3=3] int32 a;
+        };
+        [Attr4=4] union MyUnion {
+          [Attr5=5] int32 a;
+        };
+        [Attr6=6] enum MyEnum {
+          [Attr7=7] a
+        };
+        [Attr8=8] interface MyInterface {
+          [Attr9=9] MyMethod([Attr10=10] int32 a) => ([Attr11=11] bool b);
+        };
+        [Attr12=12] const double kMyConst = 1.23;
+        """
+    expected4 = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'),
+                   ast.AttributeList([ast.Attribute("Attr0", 0)])),
+        ast.ImportList(
+            ast.Import(
+                ast.AttributeList([ast.Attribute("Attr1", 1)]), "my_import")),
+        [
+            ast.Struct(
+                'MyStruct', ast.AttributeList(ast.Attribute("Attr2", 2)),
+                ast.StructBody(
+                    ast.StructField(
+                        'a', ast.AttributeList([ast.Attribute("Attr3", 3)]),
+                        None, 'int32', None))),
+            ast.Union(
+                'MyUnion', ast.AttributeList(ast.Attribute("Attr4", 4)),
+                ast.UnionBody(
+                    ast.UnionField(
+                        'a', ast.AttributeList([ast.Attribute("Attr5", 5)]),
+                        None, 'int32'))),
+            ast.Enum(
+                'MyEnum', ast.AttributeList(ast.Attribute("Attr6", 6)),
+                ast.EnumValueList(
+                    ast.EnumValue(
+                        'VALUE', ast.AttributeList([ast.Attribute("Attr7", 7)]),
+                        None))),
+            ast.Interface(
+                'MyInterface', ast.AttributeList(ast.Attribute("Attr8", 8)),
+                ast.InterfaceBody(
+                    ast.Method(
+                        'MyMethod', ast.AttributeList(
+                            ast.Attribute("Attr9", 9)), None,
+                        ast.ParameterList(
+                            ast.Parameter(
+                                'a',
+                                ast.AttributeList([ast.Attribute("Attr10", 10)
+                                                   ]), None, 'int32')),
+                        ast.ParameterList(
+                            ast.Parameter(
+                                'b',
+                                ast.AttributeList([ast.Attribute("Attr11", 11)
+                                                   ]), None, 'bool'))))),
+            ast.Const('kMyConst', ast.AttributeList(
+                ast.Attribute("Attr12", 12)), 'double', '1.23')
+        ])
+    self.assertEquals(parser.Parse(source4, "my_file.mojom"), expected4)
+
+    # TODO(vtl): Boolean attributes don't work yet. (In fact, we just |eval()|
+    # literal (non-name) values, which is extremely dubious.)
+
+  def testInvalidAttributes(self):
+    """Tests that invalid attributes and attribute lists are correctly
+    detected."""
+
+    # Trailing commas not allowed.
+    source1 = "[MyAttribute=MyName,] struct MyStruct {};"
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:1: Error: Unexpected '\]':\n"
+        r"\[MyAttribute=MyName,\] struct MyStruct {};$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    # Missing value.
+    source2 = "[MyAttribute=] struct MyStruct {};"
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:1: Error: Unexpected '\]':\n"
+        r"\[MyAttribute=\] struct MyStruct {};$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    # Missing key.
+    source3 = "[=MyName] struct MyStruct {};"
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:1: Error: Unexpected '=':\n"
+        r"\[=MyName\] struct MyStruct {};$"):
+      parser.Parse(source3, "my_file.mojom")
+
+  def testValidImports(self):
+    """Tests parsing import statements."""
+
+    # One import (no module statement).
+    source1 = "import \"somedir/my.mojom\";"
+    expected1 = ast.Mojom(None,
+                          ast.ImportList(ast.Import(None, "somedir/my.mojom")),
+                          [])
+    self.assertEquals(parser.Parse(source1, "my_file.mojom"), expected1)
+
+    # Two imports (no module statement).
+    source2 = """\
+        import "somedir/my1.mojom";
+        import "somedir/my2.mojom";
+        """
+    expected2 = ast.Mojom(
+        None,
+        ast.ImportList([
+            ast.Import(None, "somedir/my1.mojom"),
+            ast.Import(None, "somedir/my2.mojom")
+        ]), [])
+    self.assertEquals(parser.Parse(source2, "my_file.mojom"), expected2)
+
+    # Imports with module statement.
+    source3 = """\
+        module my_module;
+        import "somedir/my1.mojom";
+        import "somedir/my2.mojom";
+        """
+    expected3 = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None),
+        ast.ImportList([
+            ast.Import(None, "somedir/my1.mojom"),
+            ast.Import(None, "somedir/my2.mojom")
+        ]), [])
+    self.assertEquals(parser.Parse(source3, "my_file.mojom"), expected3)
+
+  def testInvalidImports(self):
+    """Tests that invalid import statements are correctly detected."""
+
+    source1 = """\
+        // Make the error occur on line 2.
+        import invalid
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'invalid':\n"
+        r" *import invalid$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        import  // Missing string.
+        struct MyStruct {
+          int32 a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'struct':\n"
+        r" *struct MyStruct {$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        import "foo.mojom"  // Missing semicolon.
+        struct MyStruct {
+          int32 a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'struct':\n"
+        r" *struct MyStruct {$"):
+      parser.Parse(source3, "my_file.mojom")
+
+  def testValidNullableTypes(self):
+    """Tests parsing nullable types."""
+
+    source = """\
+        struct MyStruct {
+          int32? a;  // This is actually invalid, but handled at a different
+                     // level.
+          string? b;
+          array<int32> ? c;
+          array<string ? > ? d;
+          array<array<int32>?>? e;
+          array<int32, 1>? f;
+          array<string?, 1>? g;
+          some_struct? h;
+          handle? i;
+          handle<data_pipe_consumer>? j;
+          handle<data_pipe_producer>? k;
+          handle<message_pipe>? l;
+          handle<shared_buffer>? m;
+          pending_receiver<some_interface>? n;
+          handle<platform>? o;
+        };
+        """
+    expected = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.StructField('a', None, None, 'int32?', None),
+                ast.StructField('b', None, None, 'string?', None),
+                ast.StructField('c', None, None, 'int32[]?', None),
+                ast.StructField('d', None, None, 'string?[]?', None),
+                ast.StructField('e', None, None, 'int32[]?[]?', None),
+                ast.StructField('f', None, None, 'int32[1]?', None),
+                ast.StructField('g', None, None, 'string?[1]?', None),
+                ast.StructField('h', None, None, 'some_struct?', None),
+                ast.StructField('i', None, None, 'handle?', None),
+                ast.StructField('j', None, None, 'handle<data_pipe_consumer>?',
+                                None),
+                ast.StructField('k', None, None, 'handle<data_pipe_producer>?',
+                                None),
+                ast.StructField('l', None, None, 'handle<message_pipe>?', None),
+                ast.StructField('m', None, None, 'handle<shared_buffer>?',
+                                None),
+                ast.StructField('n', None, None, 'rcv<some_interface>?', None),
+                ast.StructField('o', None, None, 'handle<platform>?', None)
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source, "my_file.mojom"), expected)
+
+  def testInvalidNullableTypes(self):
+    """Tests that invalid nullable types are correctly detected."""
+    source1 = """\
+        struct MyStruct {
+          string?? a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected '\?':\n"
+        r" *string\?\? a;$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        struct MyStruct {
+          handle?<data_pipe_consumer> a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected '<':\n"
+        r" *handle\?<data_pipe_consumer> a;$"):
+      parser.Parse(source2, "my_file.mojom")
+
+  def testSimpleUnion(self):
+    """Tests a simple .mojom source that just defines a union."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          int32 a;
+          double b;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Union(
+                'MyUnion', None,
+                ast.UnionBody([
+                    ast.UnionField('a', None, None, 'int32'),
+                    ast.UnionField('b', None, None, 'double')
+                ]))
+        ])
+    actual = parser.Parse(source, "my_file.mojom")
+    self.assertEquals(actual, expected)
+
+  def testUnionWithOrdinals(self):
+    """Test that ordinals are assigned to fields."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          int32 a @10;
+          double b @30;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Union(
+                'MyUnion', None,
+                ast.UnionBody([
+                    ast.UnionField('a', None, ast.Ordinal(10), 'int32'),
+                    ast.UnionField('b', None, ast.Ordinal(30), 'double')
+                ]))
+        ])
+    actual = parser.Parse(source, "my_file.mojom")
+    self.assertEquals(actual, expected)
+
+  def testUnionWithStructMembers(self):
+    """Test that struct members are accepted."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          SomeStruct s;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Union(
+                'MyUnion', None,
+                ast.UnionBody([ast.UnionField('s', None, None, 'SomeStruct')]))
+        ])
+    actual = parser.Parse(source, "my_file.mojom")
+    self.assertEquals(actual, expected)
+
+  def testUnionWithArrayMember(self):
+    """Test that array members are accepted."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          array<int32> a;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Union(
+                'MyUnion', None,
+                ast.UnionBody([ast.UnionField('a', None, None, 'int32[]')]))
+        ])
+    actual = parser.Parse(source, "my_file.mojom")
+    self.assertEquals(actual, expected)
+
+  def testUnionWithMapMember(self):
+    """Test that map members are accepted."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          map<int32, string> m;
+        };
+        """
+    expected = ast.Mojom(
+        ast.Module(('IDENTIFIER', 'my_module'), None), ast.ImportList(), [
+            ast.Union(
+                'MyUnion', None,
+                ast.UnionBody(
+                    [ast.UnionField('m', None, None, 'string{int32}')]))
+        ])
+    actual = parser.Parse(source, "my_file.mojom")
+    self.assertEquals(actual, expected)
+
+  def testUnionDisallowNestedStruct(self):
+    """Tests that structs cannot be nested in unions."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          struct MyStruct {
+            int32 a;
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:4: Error: Unexpected 'struct':\n"
+        r" *struct MyStruct {$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testUnionDisallowNestedInterfaces(self):
+    """Tests that interfaces cannot be nested in unions."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          interface MyInterface {
+            MyMethod(int32 a);
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:4: Error: Unexpected 'interface':\n"
+        r" *interface MyInterface {$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testUnionDisallowNestedUnion(self):
+    """Tests that unions cannot be nested in unions."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          union MyOtherUnion {
+            int32 a;
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:4: Error: Unexpected 'union':\n"
+        r" *union MyOtherUnion {$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testUnionDisallowNestedEnum(self):
+    """Tests that enums cannot be nested in unions."""
+    source = """\
+        module my_module;
+
+        union MyUnion {
+          enum MyEnum {
+            A,
+          };
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:4: Error: Unexpected 'enum':\n"
+        r" *enum MyEnum {$"):
+      parser.Parse(source, "my_file.mojom")
+
+  def testValidAssociatedKinds(self):
+    """Tests parsing associated interfaces and requests."""
+    source1 = """\
+        struct MyStruct {
+          associated MyInterface a;
+          pending_associated_receiver<MyInterface> b;
+          associated MyInterface? c;
+          pending_associated_receiver<MyInterface>? d;
+        };
+        """
+    expected1 = ast.Mojom(None, ast.ImportList(), [
+        ast.Struct(
+            'MyStruct', None,
+            ast.StructBody([
+                ast.StructField('a', None, None, 'asso<MyInterface>', None),
+                ast.StructField('b', None, None, 'rca<MyInterface>', None),
+                ast.StructField('c', None, None, 'asso<MyInterface>?', None),
+                ast.StructField('d', None, None, 'rca<MyInterface>?', None)
+            ]))
+    ])
+    self.assertEquals(parser.Parse(source1, "my_file.mojom"), expected1)
+
+    source2 = """\
+        interface MyInterface {
+          MyMethod(associated A a) =>(pending_associated_receiver<B> b);
+        };"""
+    expected2 = ast.Mojom(None, ast.ImportList(), [
+        ast.Interface(
+            'MyInterface', None,
+            ast.InterfaceBody(
+                ast.Method(
+                    'MyMethod', None, None,
+                    ast.ParameterList(ast.Parameter('a', None, None,
+                                                    'asso<A>')),
+                    ast.ParameterList(ast.Parameter('b', None, None,
+                                                    'rca<B>')))))
+    ])
+    self.assertEquals(parser.Parse(source2, "my_file.mojom"), expected2)
+
+  def testInvalidAssociatedKinds(self):
+    """Tests that invalid associated interfaces and requests are correctly
+    detected."""
+    source1 = """\
+        struct MyStruct {
+          associated associated SomeInterface a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError,
+        r"^my_file\.mojom:2: Error: Unexpected 'associated':\n"
+        r" *associated associated SomeInterface a;$"):
+      parser.Parse(source1, "my_file.mojom")
+
+    source2 = """\
+        struct MyStruct {
+          associated handle a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected 'handle':\n"
+        r" *associated handle a;$"):
+      parser.Parse(source2, "my_file.mojom")
+
+    source3 = """\
+        struct MyStruct {
+          associated? MyInterface& a;
+        };
+        """
+    with self.assertRaisesRegexp(
+        parser.ParseError, r"^my_file\.mojom:2: Error: Unexpected '\?':\n"
+        r" *associated\? MyInterface& a;$"):
+      parser.Parse(source3, "my_file.mojom")
+
+if __name__ == "__main__":
+  unittest.main()
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser.py
new file mode 100755
index 00000000..9693090e
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser.py
@@ -0,0 +1,502 @@
+#!/usr/bin/env python3
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Parses mojom IDL files.
+
+This script parses one or more input mojom files and produces corresponding
+module files fully describing the definitions contained within each mojom. The
+module data is pickled and can be easily consumed by other tools to, e.g.,
+generate usable language bindings.
+"""
+
+import argparse
+import builtins
+import codecs
+import errno
+import json
+import logging
+import multiprocessing
+import os
+import os.path
+import sys
+import traceback
+from collections import defaultdict
+
+from mojom.generate import module
+from mojom.generate import translate
+from mojom.parse import parser
+from mojom.parse import conditional_features
+
+
+# Disable this for easier debugging.
+_ENABLE_MULTIPROCESSING = True
+
+# https://docs.python.org/3/library/multiprocessing.html#:~:text=bpo-33725
+if __name__ == '__main__' and sys.platform == 'darwin':
+  multiprocessing.set_start_method('fork')
+_MULTIPROCESSING_USES_FORK = multiprocessing.get_start_method() == 'fork'
+
+
+def _ResolveRelativeImportPath(path, roots):
+  """Attempts to resolve a relative import path against a set of possible roots.
+
+  Args:
+    path: The relative import path to resolve.
+    roots: A list of absolute paths which will be checked in descending length
+        order for a match against path.
+
+  Returns:
+    A normalized absolute path combining one of the roots with the input path if
+    and only if such a file exists.
+
+  Raises:
+    ValueError: The path could not be resolved against any of the given roots.
+  """
+  for root in reversed(sorted(roots, key=len)):
+    abs_path = os.path.join(root, path)
+    if os.path.isfile(abs_path):
+      return os.path.normcase(os.path.normpath(abs_path))
+
+  raise ValueError('"%s" does not exist in any of %s' % (path, roots))
+
+
+def RebaseAbsolutePath(path, roots):
+  """Rewrites an absolute file path as relative to an absolute directory path in
+  roots.
+
+  Args:
+    path: The absolute path of an existing file.
+    roots: A list of absolute directory paths. The given path argument must fall
+        within one of these directories.
+
+  Returns:
+    A path equivalent to the input path, but relative to one of the provided
+    roots. If the input path falls within multiple roots, the longest root is
+    chosen (and thus the shortest relative path is returned).
+
+    Paths returned by this method always use forward slashes as a separator to
+    mirror mojom import syntax.
+
+  Raises:
+    ValueError if the given path does not fall within any of the listed roots.
+  """
+  assert os.path.isabs(path)
+  assert os.path.isfile(path)
+  assert all(map(os.path.isabs, roots))
+
+  sorted_roots = list(reversed(sorted(roots, key=len)))
+
+  def try_rebase_path(path, root):
+    head, rebased_path = os.path.split(path)
+    while head != root:
+      head, tail = os.path.split(head)
+      if not tail:
+        return None
+      rebased_path = os.path.join(tail, rebased_path)
+    return rebased_path
+
+  for root in sorted_roots:
+    relative_path = try_rebase_path(path, root)
+    if relative_path:
+      # TODO(crbug.com/953884): Use pathlib for this kind of thing once we're
+      # fully migrated to Python 3.
+      return relative_path.replace('\\', '/')
+
+  raise ValueError('%s does not fall within any of %s' % (path, sorted_roots))
+
+
+def _GetModuleFilename(mojom_filename):
+  return mojom_filename + '-module'
+
+
+def _EnsureInputLoaded(mojom_abspath, module_path, abs_paths, asts,
+                       dependencies, loaded_modules, module_metadata):
+  """Recursively ensures that a module and its dependencies are loaded.
+
+  Args:
+    mojom_abspath: An absolute file path pointing to a mojom file to load.
+    module_path: The relative path used to identify mojom_abspath.
+    abs_paths: A mapping from module paths to absolute file paths for all
+        inputs given to this execution of the script.
+    asts: A map from each input mojom's absolute path to its parsed AST.
+    dependencies: A mapping of which input mojoms depend on each other, indexed
+        by absolute file path.
+    loaded_modules: A mapping of all modules loaded so far, including non-input
+        modules that were pulled in as transitive dependencies of the inputs.
+    module_metadata: Metadata to be attached to every module loaded by this
+        helper.
+
+  Returns:
+    None
+
+    On return, loaded_modules will be populated with the loaded input mojom's
+    Module as well as the Modules of all of its transitive dependencies."""
+
+  if mojom_abspath in loaded_modules:
+    # Already done.
+    return
+
+  for dep_abspath, dep_path in sorted(dependencies[mojom_abspath]):
+    if dep_abspath not in loaded_modules:
+      _EnsureInputLoaded(dep_abspath, dep_path, abs_paths, asts, dependencies,
+                         loaded_modules, module_metadata)
+
+  imports = {}
+  for imp in asts[mojom_abspath].import_list:
+    path = imp.import_filename
+    imports[path] = loaded_modules[abs_paths[path]]
+  loaded_modules[mojom_abspath] = translate.OrderedModule(
+      asts[mojom_abspath], module_path, imports)
+  loaded_modules[mojom_abspath].metadata = dict(module_metadata)
+
+
+def _CollectAllowedImportsFromBuildMetadata(build_metadata_filename):
+  allowed_imports = set()
+  processed_deps = set()
+
+  def collect(metadata_filename):
+    processed_deps.add(metadata_filename)
+
+    # Paths in the metadata file are relative to the metadata file's dir.
+    metadata_dir = os.path.abspath(os.path.dirname(metadata_filename))
+
+    def to_abs(s):
+      return os.path.normpath(os.path.join(metadata_dir, s))
+
+    with open(metadata_filename) as f:
+      metadata = json.load(f)
+      allowed_imports.update(
+          [os.path.normcase(to_abs(s)) for s in metadata['sources']])
+      for dep_metadata in metadata['deps']:
+        dep_metadata = to_abs(dep_metadata)
+        if dep_metadata not in processed_deps:
+          collect(dep_metadata)
+
+  collect(build_metadata_filename)
+  return allowed_imports
+
+
+# multiprocessing helper.
+def _ParseAstHelper(mojom_abspath, enabled_features):
+  with codecs.open(mojom_abspath, encoding='utf-8') as f:
+    ast = parser.Parse(f.read(), mojom_abspath)
+    conditional_features.RemoveDisabledDefinitions(ast, enabled_features)
+    return mojom_abspath, ast
+
+
+# multiprocessing helper.
+def _SerializeHelper(mojom_abspath, mojom_path):
+  module_path = os.path.join(_SerializeHelper.output_root_path,
+                             _GetModuleFilename(mojom_path))
+  module_dir = os.path.dirname(module_path)
+  if not os.path.exists(module_dir):
+    try:
+      # Python 2 doesn't support exist_ok on makedirs(), so we just ignore
+      # that failure if it happens. It's possible during build due to races
+      # among build steps with module outputs in the same directory.
+      os.makedirs(module_dir)
+    except OSError as e:
+      if e.errno != errno.EEXIST:
+        raise
+  with open(module_path, 'wb') as f:
+    _SerializeHelper.loaded_modules[mojom_abspath].Dump(f)
+
+
+class _ExceptionWrapper:
+  def __init__(self):
+    # Do not capture exception object to ensure pickling works.
+    self.formatted_trace = traceback.format_exc()
+
+
+class _FuncWrapper:
+  """Marshals exceptions and spreads args."""
+
+  def __init__(self, func):
+    self._func = func
+
+  def __call__(self, args):
+    # multiprocessing does not gracefully handle excptions.
+    # https://crbug.com/1219044
+    try:
+      return self._func(*args)
+    except:  # pylint: disable=bare-except
+      return _ExceptionWrapper()
+
+
+def _Shard(target_func, arg_list, processes=None):
+  arg_list = list(arg_list)
+  if processes is None:
+    processes = multiprocessing.cpu_count()
+  # Seems optimal to have each process perform at least 2 tasks.
+  processes = min(processes, len(arg_list) // 2)
+
+  if sys.platform == 'win32':
+    # TODO(crbug.com/1190269) - we can't use more than 56
+    # cores on Windows or Python3 may hang.
+    processes = min(processes, 56)
+
+  # Don't spin up processes unless there is enough work to merit doing so.
+  if not _ENABLE_MULTIPROCESSING or processes < 2:
+    for arg_tuple in arg_list:
+      yield target_func(*arg_tuple)
+    return
+
+  pool = multiprocessing.Pool(processes=processes)
+  try:
+    wrapped_func = _FuncWrapper(target_func)
+    for result in pool.imap_unordered(wrapped_func, arg_list):
+      if isinstance(result, _ExceptionWrapper):
+        sys.stderr.write(result.formatted_trace)
+        sys.exit(1)
+      yield result
+  finally:
+    pool.close()
+    pool.join()  # Needed on Windows to avoid WindowsError during terminate.
+    pool.terminate()
+
+
+def _ParseMojoms(mojom_files,
+                 input_root_paths,
+                 output_root_path,
+                 module_root_paths,
+                 enabled_features,
+                 module_metadata,
+                 allowed_imports=None):
+  """Parses a set of mojom files and produces serialized module outputs.
+
+  Args:
+    mojom_files: A list of mojom files to process. Paths must be absolute paths
+        which fall within one of the input or output root paths.
+    input_root_paths: A list of absolute filesystem paths which may be used to
+        resolve relative mojom file paths.
+    output_root_path: An absolute filesystem path which will service as the root
+        for all emitted artifacts. Artifacts produced from a given mojom file
+        are based on the mojom's relative path, rebased onto this path.
+        Additionally, the script expects this root to contain already-generated
+        modules for any transitive dependencies not listed in mojom_files.
+    module_root_paths: A list of absolute filesystem paths which contain
+        already-generated modules for any non-transitive dependencies.
+    enabled_features: A list of enabled feature names, controlling which AST
+        nodes are filtered by [EnableIf] or [EnableIfNot] attributes.
+    module_metadata: A list of 2-tuples representing metadata key-value pairs to
+        attach to each compiled module output.
+
+  Returns:
+    None.
+
+    Upon completion, a mojom-module file will be saved for each input mojom.
+  """
+  assert input_root_paths
+  assert output_root_path
+
+  loaded_mojom_asts = {}
+  loaded_modules = {}
+  input_dependencies = defaultdict(set)
+  mojom_files_to_parse = dict((os.path.normcase(abs_path),
+                               RebaseAbsolutePath(abs_path, input_root_paths))
+                              for abs_path in mojom_files)
+  abs_paths = dict(
+      (path, abs_path) for abs_path, path in mojom_files_to_parse.items())
+
+  logging.info('Parsing %d .mojom into ASTs', len(mojom_files_to_parse))
+  map_args = ((mojom_abspath, enabled_features)
+              for mojom_abspath in mojom_files_to_parse)
+  for mojom_abspath, ast in _Shard(_ParseAstHelper, map_args):
+    loaded_mojom_asts[mojom_abspath] = ast
+
+  logging.info('Processing dependencies')
+  for mojom_abspath, ast in sorted(loaded_mojom_asts.items()):
+    invalid_imports = []
+    for imp in ast.import_list:
+      import_abspath = _ResolveRelativeImportPath(imp.import_filename,
+                                                  input_root_paths)
+      if allowed_imports and import_abspath not in allowed_imports:
+        invalid_imports.append(imp.import_filename)
+
+      abs_paths[imp.import_filename] = import_abspath
+      if import_abspath in mojom_files_to_parse:
+        # This import is in the input list, so we're going to translate it
+        # into a module below; however it's also a dependency of another input
+        # module. We retain record of dependencies to help with input
+        # processing later.
+        input_dependencies[mojom_abspath].add(
+            (import_abspath, imp.import_filename))
+      elif import_abspath not in loaded_modules:
+        # We have an import that isn't being parsed right now. It must already
+        # be parsed and have a module file sitting in a corresponding output
+        # location.
+        module_path = _GetModuleFilename(imp.import_filename)
+        module_abspath = _ResolveRelativeImportPath(
+            module_path, module_root_paths + [output_root_path])
+        with open(module_abspath, 'rb') as module_file:
+          loaded_modules[import_abspath] = module.Module.Load(module_file)
+
+    if invalid_imports:
+      raise ValueError(
+          '\nThe file %s imports the following files not allowed by build '
+          'dependencies:\n\n%s\n' % (mojom_abspath, '\n'.join(invalid_imports)))
+  logging.info('Loaded %d modules from dependencies', len(loaded_modules))
+
+  # At this point all transitive imports not listed as inputs have been loaded
+  # and we have a complete dependency tree of the unprocessed inputs. Now we can
+  # load all the inputs, resolving dependencies among them recursively as we go.
+  logging.info('Ensuring inputs are loaded')
+  num_existing_modules_loaded = len(loaded_modules)
+  for mojom_abspath, mojom_path in mojom_files_to_parse.items():
+    _EnsureInputLoaded(mojom_abspath, mojom_path, abs_paths, loaded_mojom_asts,
+                       input_dependencies, loaded_modules, module_metadata)
+  assert (num_existing_modules_loaded +
+          len(mojom_files_to_parse) == len(loaded_modules))
+
+  # Now we have fully translated modules for every input and every transitive
+  # dependency. We can dump the modules to disk for other tools to use.
+  logging.info('Serializing %d modules', len(mojom_files_to_parse))
+
+  # Windows does not use fork() for multiprocessing, so we'd need to pass
+  # loaded_module via IPC rather than via globals. Doing so is slower than not
+  # using multiprocessing.
+  _SerializeHelper.loaded_modules = loaded_modules
+  _SerializeHelper.output_root_path = output_root_path
+  # Doesn't seem to help past 4. Perhaps IO bound here?
+  processes = 4 if _MULTIPROCESSING_USES_FORK else 0
+  map_args = mojom_files_to_parse.items()
+  for _ in _Shard(_SerializeHelper, map_args, processes=processes):
+    pass
+
+
+def Run(command_line):
+  debug_logging = os.environ.get('MOJOM_PARSER_DEBUG', '0') != '0'
+  logging.basicConfig(level=logging.DEBUG if debug_logging else logging.WARNING,
+                      format='%(levelname).1s %(relativeCreated)6d %(message)s')
+  logging.info('Started (%s)', os.path.basename(sys.argv[0]))
+
+  arg_parser = argparse.ArgumentParser(
+      description="""
+Parses one or more mojom files and produces corresponding module outputs fully
+describing the definitions therein. The output is exhaustive, stable, and
+sufficient for another tool to consume and emit e.g. usable language
+bindings based on the original mojoms.""",
+      epilog="""
+Note that each transitive import dependency reachable from the input mojoms must
+either also be listed as an input or must have its corresponding compiled module
+already present in the provided output root.""")
+
+  arg_parser.add_argument(
+      '--input-root',
+      default=[],
+      action='append',
+      metavar='ROOT',
+      dest='input_root_paths',
+      help='Adds ROOT to the set of root paths against which relative input '
+      'paths should be resolved. Provided root paths are always searched '
+      'in order from longest absolute path to shortest.')
+  arg_parser.add_argument(
+      '--output-root',
+      action='store',
+      required=True,
+      dest='output_root_path',
+      metavar='ROOT',
+      help='Use ROOT as the root path in which the parser should emit compiled '
+      'modules for each processed input mojom. The path of emitted module is '
+      'based on the relative input path, rebased onto this root. Note that '
+      'ROOT is also searched for existing modules of any transitive imports '
+      'which were not included in the set of inputs.')
+  arg_parser.add_argument(
+      '--module-root',
+      default=[],
+      action='append',
+      metavar='ROOT',
+      dest='module_root_paths',
+      help='Adds ROOT to the set of root paths to search for existing modules '
+      'of non-transitive imports. Provided root paths are always searched in '
+      'order from longest absolute path to shortest.')
+  arg_parser.add_argument(
+      '--mojoms',
+      nargs='+',
+      dest='mojom_files',
+      default=[],
+      metavar='MOJOM_FILE',
+      help='Input mojom filename(s). Each filename must be either an absolute '
+      'path which falls within one of the given input or output roots, or a '
+      'relative path the parser will attempt to resolve using each of those '
+      'roots in unspecified order.')
+  arg_parser.add_argument(
+      '--mojom-file-list',
+      action='store',
+      metavar='LIST_FILENAME',
+      help='Input file whose contents are a list of mojoms to process. This '
+      'may be provided in lieu of --mojoms to avoid hitting command line '
+      'length limtations')
+  arg_parser.add_argument(
+      '--enable-feature',
+      dest='enabled_features',
+      default=[],
+      action='append',
+      metavar='FEATURE',
+      help='Enables a named feature when parsing the given mojoms. Features '
+      'are identified by arbitrary string values. Specifying this flag with a '
+      'given FEATURE name will cause the parser to process any syntax elements '
+      'tagged with an [EnableIf=FEATURE] or [EnableIfNot] attribute. If this '
+      'flag is not provided for a given FEATURE, such tagged elements are '
+      'discarded by the parser and will not be present in the compiled output.')
+  arg_parser.add_argument(
+      '--check-imports',
+      dest='build_metadata_filename',
+      action='store',
+      metavar='METADATA_FILENAME',
+      help='Instructs the parser to check imports against a set of allowed '
+      'imports. Allowed imports are based on build metadata within '
+      'METADATA_FILENAME. This is a JSON file with a `sources` key listing '
+      'paths to the set of input mojom files being processed by this parser '
+      'run, and a `deps` key listing paths to metadata files for any '
+      'dependencies of these inputs. This feature can be used to implement '
+      'build-time dependency checking for mojom imports, where each build '
+      'metadata file corresponds to a build target in the dependency graph of '
+      'a typical build system.')
+  arg_parser.add_argument(
+      '--add-module-metadata',
+      dest='module_metadata',
+      default=[],
+      action='append',
+      metavar='KEY=VALUE',
+      help='Adds a metadata key-value pair to the output module. This can be '
+      'used by build toolchains to augment parsed mojom modules with product-'
+      'specific metadata for later extraction and use by custom bindings '
+      'generators.')
+
+  args, _ = arg_parser.parse_known_args(command_line)
+  if args.mojom_file_list:
+    with open(args.mojom_file_list) as f:
+      args.mojom_files.extend(f.read().split())
+
+  if not args.mojom_files:
+    raise ValueError(
+        'Must list at least one mojom file via --mojoms or --mojom-file-list')
+
+  mojom_files = list(map(os.path.abspath, args.mojom_files))
+  input_roots = list(map(os.path.abspath, args.input_root_paths))
+  output_root = os.path.abspath(args.output_root_path)
+  module_roots = list(map(os.path.abspath, args.module_root_paths))
+
+  if args.build_metadata_filename:
+    allowed_imports = _CollectAllowedImportsFromBuildMetadata(
+        args.build_metadata_filename)
+  else:
+    allowed_imports = None
+
+  module_metadata = list(
+      map(lambda kvp: tuple(kvp.split('=')), args.module_metadata))
+  _ParseMojoms(mojom_files, input_roots, output_root, module_roots,
+               args.enabled_features, module_metadata, allowed_imports)
+  logging.info('Finished')
+
+
+if __name__ == '__main__':
+  Run(sys.argv[1:])
+  # Exit without running GC, which can save multiple seconds due to the large
+  # number of object created. But flush is necessary as os._exit doesn't do
+  # that.
+  sys.stdout.flush()
+  sys.stderr.flush()
+  os._exit(0)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser_test_case.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser_test_case.py
new file mode 100644
index 00000000..f0ee6966
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser_test_case.py
@@ -0,0 +1,73 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import json
+import os
+import os.path
+import shutil
+import tempfile
+import unittest
+
+import mojom_parser
+
+from mojom.generate import module
+
+
+class MojomParserTestCase(unittest.TestCase):
+  """Tests covering the behavior defined by the main mojom_parser.py script.
+  This includes behavior around input and output path manipulation, dependency
+  resolution, and module serialization and deserialization."""
+
+  def __init__(self, method_name):
+    super().__init__(method_name)
+    self._temp_dir = None
+
+  def setUp(self):
+    self._temp_dir = tempfile.mkdtemp()
+
+  def tearDown(self):
+    shutil.rmtree(self._temp_dir)
+    self._temp_dir = None
+
+  def GetPath(self, path):
+    assert not os.path.isabs(path)
+    return os.path.join(self._temp_dir, path)
+
+  def GetModulePath(self, path):
+    assert not os.path.isabs(path)
+    return os.path.join(self.GetPath('out'), path) + '-module'
+
+  def WriteFile(self, path, contents):
+    full_path = self.GetPath(path)
+    dirname = os.path.dirname(full_path)
+    if not os.path.exists(dirname):
+      os.makedirs(dirname)
+    with open(full_path, 'w') as f:
+      f.write(contents)
+
+  def LoadModule(self, mojom_path):
+    with open(self.GetModulePath(mojom_path), 'rb') as f:
+      return module.Module.Load(f)
+
+  def ParseMojoms(self, mojoms, metadata=None):
+    """Parse all input mojoms relative the temp dir."""
+    out_dir = self.GetPath('out')
+    args = [
+        '--input-root', self._temp_dir, '--input-root', out_dir,
+        '--output-root', out_dir, '--mojoms'
+    ] + list(map(lambda mojom: os.path.join(self._temp_dir, mojom), mojoms))
+    if metadata:
+      args.extend(['--check-imports', self.GetPath(metadata)])
+    mojom_parser.Run(args)
+
+  def ExtractTypes(self, mojom):
+    filename = 'test.mojom'
+    self.WriteFile(filename, mojom)
+    self.ParseMojoms([filename])
+    m = self.LoadModule(filename)
+    definitions = {}
+    for kinds in (m.enums, m.structs, m.unions, m.interfaces, m.features):
+      for kind in kinds:
+        definitions[kind.mojom_name] = kind
+    return definitions
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser_unittest.py
new file mode 100644
index 00000000..353a2b6e
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/mojom_parser_unittest.py
@@ -0,0 +1,186 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import json
+
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class MojomParserTest(MojomParserTestCase):
+  """Tests covering the behavior defined by the main mojom_parser.py script.
+  This includes behavior around input and output path manipulation, dependency
+  resolution, and module serialization and deserialization."""
+
+  def testBasicParse(self):
+    """Basic test to verify that we can parse a mojom file and get a module."""
+    mojom = 'foo/bar.mojom'
+    self.WriteFile(
+        mojom, """\
+        module test;
+        enum TestEnum { kFoo };
+        """)
+    self.ParseMojoms([mojom])
+
+    m = self.LoadModule(mojom)
+    self.assertEqual('foo/bar.mojom', m.path)
+    self.assertEqual('test', m.mojom_namespace)
+    self.assertEqual(1, len(m.enums))
+
+  def testBasicParseWithAbsolutePaths(self):
+    """Verifies that we can parse a mojom file given an absolute path input."""
+    mojom = 'foo/bar.mojom'
+    self.WriteFile(
+        mojom, """\
+        module test;
+        enum TestEnum { kFoo };
+        """)
+    self.ParseMojoms([self.GetPath(mojom)])
+
+    m = self.LoadModule(mojom)
+    self.assertEqual('foo/bar.mojom', m.path)
+    self.assertEqual('test', m.mojom_namespace)
+    self.assertEqual(1, len(m.enums))
+
+  def testImport(self):
+    """Verify imports within the same set of mojom inputs."""
+    a = 'a.mojom'
+    b = 'b.mojom'
+    self.WriteFile(
+        a, """\
+        module a;
+        import "b.mojom";
+        struct Foo { b.Bar bar; };""")
+    self.WriteFile(b, """\
+        module b;
+        struct Bar {};""")
+    self.ParseMojoms([a, b])
+
+    ma = self.LoadModule(a)
+    mb = self.LoadModule(b)
+    self.assertEqual('a.mojom', ma.path)
+    self.assertEqual('b.mojom', mb.path)
+    self.assertEqual(1, len(ma.imports))
+    self.assertEqual(mb, ma.imports[0])
+
+  def testPreProcessedImport(self):
+    """Verify imports processed by a previous parser execution can be loaded
+    properly when parsing a dependent mojom."""
+    a = 'a.mojom'
+    self.WriteFile(a, """\
+        module a;
+        struct Bar {};""")
+    self.ParseMojoms([a])
+
+    b = 'b.mojom'
+    self.WriteFile(
+        b, """\
+        module b;
+        import "a.mojom";
+        struct Foo { a.Bar bar; };""")
+    self.ParseMojoms([b])
+
+  def testMissingImport(self):
+    """Verify that an import fails if the imported mojom does not exist."""
+    a = 'a.mojom'
+    self.WriteFile(
+        a, """\
+        module a;
+        import "non-existent.mojom";
+        struct Bar {};""")
+    with self.assertRaisesRegexp(ValueError, "does not exist"):
+      self.ParseMojoms([a])
+
+  def testUnparsedImport(self):
+    """Verify that an import fails if the imported mojom is not in the set of
+    mojoms provided to the parser on this execution AND there is no pre-existing
+    parsed output module already on disk for it."""
+    a = 'a.mojom'
+    b = 'b.mojom'
+    self.WriteFile(a, """\
+        module a;
+        struct Bar {};""")
+    self.WriteFile(
+        b, """\
+        module b;
+        import "a.mojom";
+        struct Foo { a.Bar bar; };""")
+
+    # a.mojom has not been parsed yet, so its import will fail when processing
+    # b.mojom here.
+    with self.assertRaisesRegexp(ValueError, "does not exist"):
+      self.ParseMojoms([b])
+
+  def testCheckImportsBasic(self):
+    """Verify that the parser can handle --check-imports with a valid set of
+    inputs, including support for transitive dependency resolution."""
+    a = 'a.mojom'
+    a_metadata = 'out/a.build_metadata'
+    b = 'b.mojom'
+    b_metadata = 'out/b.build_metadata'
+    c = 'c.mojom'
+    c_metadata = 'out/c.build_metadata'
+    self.WriteFile(a_metadata,
+                   json.dumps({
+                       "sources": [self.GetPath(a)],
+                       "deps": []
+                   }))
+    self.WriteFile(
+        b_metadata,
+        json.dumps({
+            "sources": [self.GetPath(b)],
+            "deps": [self.GetPath(a_metadata)]
+        }))
+    self.WriteFile(
+        c_metadata,
+        json.dumps({
+            "sources": [self.GetPath(c)],
+            "deps": [self.GetPath(b_metadata)]
+        }))
+    self.WriteFile(a, """\
+        module a;
+        struct Bar {};""")
+    self.WriteFile(
+        b, """\
+        module b;
+        import "a.mojom";
+        struct Foo { a.Bar bar; };""")
+    self.WriteFile(
+        c, """\
+        module c;
+        import "a.mojom";
+        import "b.mojom";
+        struct Baz { b.Foo foo; };""")
+    self.ParseMojoms([a], metadata=a_metadata)
+    self.ParseMojoms([b], metadata=b_metadata)
+    self.ParseMojoms([c], metadata=c_metadata)
+
+  def testCheckImportsMissing(self):
+    """Verify that the parser rejects valid input mojoms when imports don't
+    agree with build metadata given via --check-imports."""
+    a = 'a.mojom'
+    a_metadata = 'out/a.build_metadata'
+    b = 'b.mojom'
+    b_metadata = 'out/b.build_metadata'
+    self.WriteFile(a_metadata,
+                   json.dumps({
+                       "sources": [self.GetPath(a)],
+                       "deps": []
+                   }))
+    self.WriteFile(b_metadata,
+                   json.dumps({
+                       "sources": [self.GetPath(b)],
+                       "deps": []
+                   }))
+    self.WriteFile(a, """\
+        module a;
+        struct Bar {};""")
+    self.WriteFile(
+        b, """\
+        module b;
+        import "a.mojom";
+        struct Foo { a.Bar bar; };""")
+
+    self.ParseMojoms([a], metadata=a_metadata)
+    with self.assertRaisesRegexp(ValueError, "not allowed by build"):
+      self.ParseMojoms([b], metadata=b_metadata)
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/stable_attribute_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/stable_attribute_unittest.py
new file mode 100644
index 00000000..d10d69c6
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/stable_attribute_unittest.py
@@ -0,0 +1,127 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from mojom_parser_test_case import MojomParserTestCase
+
+from mojom.generate import module
+
+
+class StableAttributeTest(MojomParserTestCase):
+  """Tests covering usage of the [Stable] attribute."""
+
+  def testStableAttributeTagging(self):
+    """Verify that we recognize the [Stable] attribute on relevant definitions
+    and the resulting parser outputs are tagged accordingly."""
+    mojom = 'test.mojom'
+    self.WriteFile(
+        mojom, """\
+        [Stable] enum TestEnum { kFoo };
+        enum UnstableEnum { kBar };
+        [Stable] struct TestStruct { TestEnum a; };
+        struct UnstableStruct { UnstableEnum a; };
+        [Stable] union TestUnion { TestEnum a; TestStruct b; };
+        union UnstableUnion { UnstableEnum a; UnstableStruct b; };
+        [Stable] interface TestInterface { Foo@0(TestUnion x) => (); };
+        interface UnstableInterface { Foo(UnstableUnion x) => (); };
+        """)
+    self.ParseMojoms([mojom])
+
+    m = self.LoadModule(mojom)
+    self.assertEqual(2, len(m.enums))
+    self.assertTrue(m.enums[0].stable)
+    self.assertFalse(m.enums[1].stable)
+    self.assertEqual(2, len(m.structs))
+    self.assertTrue(m.structs[0].stable)
+    self.assertFalse(m.structs[1].stable)
+    self.assertEqual(2, len(m.unions))
+    self.assertTrue(m.unions[0].stable)
+    self.assertFalse(m.unions[1].stable)
+    self.assertEqual(2, len(m.interfaces))
+    self.assertTrue(m.interfaces[0].stable)
+    self.assertFalse(m.interfaces[1].stable)
+
+  def testStableStruct(self):
+    """A [Stable] struct is valid if all its fields are also stable."""
+    self.ExtractTypes('[Stable] struct S {};')
+    self.ExtractTypes('[Stable] struct S { int32 x; bool b; };')
+    self.ExtractTypes('[Stable] enum E { A }; [Stable] struct S { E e; };')
+    self.ExtractTypes('[Stable] struct S {}; [Stable] struct T { S s; };')
+    self.ExtractTypes(
+        '[Stable] struct S {}; [Stable] struct T { array<S> ss; };')
+    self.ExtractTypes(
+        '[Stable] interface F {}; [Stable] struct T { pending_remote<F> f; };')
+
+    with self.assertRaisesRegexp(Exception, 'because it depends on E'):
+      self.ExtractTypes('enum E { A }; [Stable] struct S { E e; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on X'):
+      self.ExtractTypes('struct X {}; [Stable] struct S { X x; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on T'):
+      self.ExtractTypes('struct T {}; [Stable] struct S { array<T> xs; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on T'):
+      self.ExtractTypes('struct T {}; [Stable] struct S { map<int32, T> xs; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on T'):
+      self.ExtractTypes('struct T {}; [Stable] struct S { map<T, int32> xs; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on F'):
+      self.ExtractTypes(
+          'interface F {}; [Stable] struct S { pending_remote<F> f; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on F'):
+      self.ExtractTypes(
+          'interface F {}; [Stable] struct S { pending_receiver<F> f; };')
+
+  def testStableUnion(self):
+    """A [Stable] union is valid if all its fields' types are also stable."""
+    self.ExtractTypes('[Stable] union U {};')
+    self.ExtractTypes('[Stable] union U { int32 x; bool b; };')
+    self.ExtractTypes('[Stable] enum E { A }; [Stable] union U { E e; };')
+    self.ExtractTypes('[Stable] struct S {}; [Stable] union U { S s; };')
+    self.ExtractTypes(
+        '[Stable] struct S {}; [Stable] union U { array<S> ss; };')
+    self.ExtractTypes(
+        '[Stable] interface F {}; [Stable] union U { pending_remote<F> f; };')
+
+    with self.assertRaisesRegexp(Exception, 'because it depends on E'):
+      self.ExtractTypes('enum E { A }; [Stable] union U { E e; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on X'):
+      self.ExtractTypes('struct X {}; [Stable] union U { X x; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on T'):
+      self.ExtractTypes('struct T {}; [Stable] union U { array<T> xs; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on T'):
+      self.ExtractTypes('struct T {}; [Stable] union U { map<int32, T> xs; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on T'):
+      self.ExtractTypes('struct T {}; [Stable] union U { map<T, int32> xs; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on F'):
+      self.ExtractTypes(
+          'interface F {}; [Stable] union U { pending_remote<F> f; };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on F'):
+      self.ExtractTypes(
+          'interface F {}; [Stable] union U { pending_receiver<F> f; };')
+
+  def testStableInterface(self):
+    """A [Stable] interface is valid if all its methods' parameter types are
+    stable, including response parameters where applicable."""
+    self.ExtractTypes('[Stable] interface F {};')
+    self.ExtractTypes('[Stable] interface F { A@0(int32 x); };')
+    self.ExtractTypes('[Stable] interface F { A@0(int32 x) => (bool b); };')
+    self.ExtractTypes("""\
+        [Stable] enum E { A, B, C };
+        [Stable] struct S {};
+        [Stable] interface F { A@0(E e, S s) => (bool b, array<S> s); };
+        """)
+
+    with self.assertRaisesRegexp(Exception, 'because it depends on E'):
+      self.ExtractTypes(
+          'enum E { A, B, C }; [Stable] interface F { A@0(E e); };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on E'):
+      self.ExtractTypes(
+          'enum E { A, B, C }; [Stable] interface F { A@0(int32 x) => (E e); };'
+      )
+    with self.assertRaisesRegexp(Exception, 'because it depends on S'):
+      self.ExtractTypes(
+          'struct S {}; [Stable] interface F { A@0(int32 x) => (S s); };')
+    with self.assertRaisesRegexp(Exception, 'because it depends on S'):
+      self.ExtractTypes(
+          'struct S {}; [Stable] interface F { A@0(S s) => (bool b); };')
+
+    with self.assertRaisesRegexp(Exception, 'explicit method ordinals'):
+      self.ExtractTypes('[Stable] interface F { A() => (); };')
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/union_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/union_unittest.py
new file mode 100644
index 00000000..6b2525e5
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/union_unittest.py
@@ -0,0 +1,44 @@
+# Copyright 2022 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class UnionTest(MojomParserTestCase):
+  """Tests union parsing behavior."""
+
+  def testExtensibleMustHaveDefault(self):
+    """Verifies that extensible unions must have a default field."""
+    mojom = 'foo.mojom'
+    self.WriteFile(mojom, 'module foo; [Extensible] union U { bool x; };')
+    with self.assertRaisesRegexp(Exception, 'must specify a \[Default\]'):
+      self.ParseMojoms([mojom])
+
+  def testExtensibleSingleDefault(self):
+    """Verifies that extensible unions must not have multiple default fields."""
+    mojom = 'foo.mojom'
+    self.WriteFile(
+        mojom, """\
+               module foo;
+               [Extensible] union U {
+                 [Default] bool x;
+                 [Default] bool y;
+               };
+               """)
+    with self.assertRaisesRegexp(Exception, 'Multiple \[Default\] fields'):
+      self.ParseMojoms([mojom])
+
+  def testExtensibleDefaultTypeValid(self):
+    """Verifies that an extensible union's default field must be nullable or
+    integral type."""
+    mojom = 'foo.mojom'
+    self.WriteFile(
+        mojom, """\
+               module foo;
+               [Extensible] union U {
+                 [Default] handle<message_pipe> p;
+               };
+               """)
+    with self.assertRaisesRegexp(Exception, 'must be nullable or integral'):
+      self.ParseMojoms([mojom])
diff --git a/utils/codegen/ipc/mojo/public/tools/mojom/version_compatibility_unittest.py b/utils/codegen/ipc/mojo/public/tools/mojom/version_compatibility_unittest.py
new file mode 100644
index 00000000..45e45ec5
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/mojom/version_compatibility_unittest.py
@@ -0,0 +1,458 @@
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from mojom.generate import module
+from mojom_parser_test_case import MojomParserTestCase
+
+
+class VersionCompatibilityTest(MojomParserTestCase):
+  """Tests covering compatibility between two versions of the same mojom type
+  definition. This coverage ensures that we can reliably detect unsafe changes
+  to definitions that are expected to tolerate version skew in production
+  environments."""
+
+  def _GetTypeCompatibilityMap(self, old_mojom, new_mojom):
+    """Helper to support the implementation of assertBackwardCompatible and
+    assertNotBackwardCompatible."""
+
+    old = self.ExtractTypes(old_mojom)
+    new = self.ExtractTypes(new_mojom)
+    self.assertEqual(set(old.keys()), set(new.keys()),
+                     'Old and new test mojoms should use the same type names.')
+
+    checker = module.BackwardCompatibilityChecker()
+    compatibility_map = {}
+    for name in old:
+      try:
+        compatibility_map[name] = checker.IsBackwardCompatible(
+            new[name], old[name])
+      except Exception:
+        compatibility_map[name] = False
+    return compatibility_map
+
+  def assertBackwardCompatible(self, old_mojom, new_mojom):
+    compatibility_map = self._GetTypeCompatibilityMap(old_mojom, new_mojom)
+    for name, compatible in compatibility_map.items():
+      if not compatible:
+        raise AssertionError(
+            'Given the old mojom:\n\n    %s\n\nand the new mojom:\n\n    %s\n\n'
+            'The new definition of %s should pass a backward-compatibiity '
+            'check, but it does not.' % (old_mojom, new_mojom, name))
+
+  def assertNotBackwardCompatible(self, old_mojom, new_mojom):
+    compatibility_map = self._GetTypeCompatibilityMap(old_mojom, new_mojom)
+    if all(compatibility_map.values()):
+      raise AssertionError(
+          'Given the old mojom:\n\n    %s\n\nand the new mojom:\n\n    %s\n\n'
+          'The new mojom should fail a backward-compatibility check, but it '
+          'does not.' % (old_mojom, new_mojom))
+
+  def testNewNonExtensibleEnumValue(self):
+    """Adding a value to a non-extensible enum breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('enum E { kFoo, kBar };',
+                                     'enum E { kFoo, kBar, kBaz };')
+
+  def testNewNonExtensibleEnumValueWithMinVersion(self):
+    """Adding a value to a non-extensible enum breaks backward-compatibility,
+    even with a new [MinVersion] specified for the value."""
+    self.assertNotBackwardCompatible(
+        'enum E { kFoo, kBar };', 'enum E { kFoo, kBar, [MinVersion=1] kBaz };')
+
+  def testNewValueInExistingVersion(self):
+    """Adding a value to an existing version is not allowed, even if the old
+    enum was marked [Extensible]. Note that it is irrelevant whether or not the
+    new enum is marked [Extensible]."""
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kFoo, kBar };',
+        'enum E { kFoo, kBar, kBaz };')
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kFoo, kBar };',
+        '[Extensible] enum E { [Default] kFoo, kBar, kBaz };')
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kFoo, [MinVersion=1] kBar };',
+        'enum E { kFoo, [MinVersion=1] kBar, [MinVersion=1] kBaz };')
+
+  def testEnumValueRemoval(self):
+    """Removal of an enum value is never valid even for [Extensible] enums."""
+    self.assertNotBackwardCompatible('enum E { kFoo, kBar };',
+                                     'enum E { kFoo };')
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kFoo, kBar };',
+        '[Extensible] enum E { [Default] kFoo };')
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kA, [MinVersion=1] kB };',
+        '[Extensible] enum E { [Default] kA, };')
+    self.assertNotBackwardCompatible(
+        """[Extensible] enum E {
+          [Default] kA,
+          [MinVersion=1] kB,
+          [MinVersion=1] kZ };""",
+        '[Extensible] enum E { [Default] kA, [MinVersion=1] kB };')
+
+  def testNewExtensibleEnumValueWithMinVersion(self):
+    """Adding a new and properly [MinVersion]'d value to an [Extensible] enum
+    is a backward-compatible change. Note that it is irrelevant whether or not
+    the new enum is marked [Extensible]."""
+    self.assertBackwardCompatible('[Extensible] enum E { [Default] kA, kB };',
+                                  'enum E { kA, kB, [MinVersion=1] kC };')
+    self.assertBackwardCompatible(
+        '[Extensible] enum E { [Default] kA, kB };',
+        '[Extensible] enum E { [Default] kA, kB, [MinVersion=1] kC };')
+    self.assertBackwardCompatible(
+        '[Extensible] enum E { [Default] kA, [MinVersion=1] kB };',
+        """[Extensible] enum E {
+          [Default] kA,
+          [MinVersion=1] kB,
+          [MinVersion=2] kC };""")
+
+  def testRenameEnumValue(self):
+    """Renaming an enum value does not affect backward-compatibility. Only
+    numeric value is relevant."""
+    self.assertBackwardCompatible('enum E { kA, kB };', 'enum E { kX, kY };')
+
+  def testAddEnumValueAlias(self):
+    """Adding new enum fields does not affect backward-compatibility if it does
+    not introduce any new numeric values."""
+    self.assertBackwardCompatible(
+        'enum E { kA, kB };', 'enum E { kA, kB, kC = kA, kD = 1, kE = kD };')
+
+  def testEnumIdentity(self):
+    """An unchanged enum is obviously backward-compatible."""
+    self.assertBackwardCompatible('enum E { kA, kB, kC };',
+                                  'enum E { kA, kB, kC };')
+
+  def testNewStructFieldUnversioned(self):
+    """Adding a new field to a struct without a new (i.e. higher than any
+    existing version) [MinVersion] tag breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('struct S { string a; };',
+                                     'struct S { string a; string b; };')
+
+  def testStructFieldRemoval(self):
+    """Removing a field from a struct breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('struct S { string a; string b; };',
+                                     'struct S { string a; };')
+
+  def testStructFieldTypeChange(self):
+    """Changing the type of an existing field always breaks
+    backward-compatibility."""
+    self.assertNotBackwardCompatible('struct S { string a; };',
+                                     'struct S { array<int32> a; };')
+
+  def testStructFieldBecomingOptional(self):
+    """Changing a field from non-optional to optional breaks
+    backward-compatibility."""
+    self.assertNotBackwardCompatible('struct S { string a; };',
+                                     'struct S { string? a; };')
+
+  def testStructFieldBecomingNonOptional(self):
+    """Changing a field from optional to non-optional breaks
+    backward-compatibility."""
+    self.assertNotBackwardCompatible('struct S { string? a; };',
+                                     'struct S { string a; };')
+
+  def testStructFieldOrderChange(self):
+    """Changing the order of fields breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('struct S { string a; bool b; };',
+                                     'struct S { bool b; string a; };')
+    self.assertNotBackwardCompatible('struct S { string a@0; bool b@1; };',
+                                     'struct S { string a@1; bool b@0; };')
+
+  def testStructFieldMinVersionChange(self):
+    """Changing the MinVersion of a field breaks backward-compatibility."""
+    self.assertNotBackwardCompatible(
+        'struct S { string a; [MinVersion=1] string? b; };',
+        'struct S { string a; [MinVersion=2] string? b; };')
+
+  def testStructFieldTypeChange(self):
+    """If a struct field's own type definition changes, the containing struct
+    is backward-compatible if and only if the field type's change is
+    backward-compatible."""
+    self.assertBackwardCompatible(
+        'struct S {}; struct T { S s; };',
+        'struct S { [MinVersion=1] int32 x; }; struct T { S s; };')
+    self.assertBackwardCompatible(
+        '[Extensible] enum E { [Default] kA }; struct S { E e; };',
+        """[Extensible] enum E {
+          [Default] kA,
+          [MinVersion=1] kB };
+          struct S { E e; };""")
+    self.assertNotBackwardCompatible(
+        'struct S {}; struct T { S s; };',
+        'struct S { int32 x; }; struct T { S s; };')
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kA }; struct S { E e; };',
+        '[Extensible] enum E { [Default] kA, kB }; struct S { E e; };')
+
+  def testNewStructFieldWithInvalidMinVersion(self):
+    """Adding a new field using an existing MinVersion breaks backward-
+    compatibility."""
+    self.assertNotBackwardCompatible(
+        """\
+        struct S {
+          string a;
+          [MinVersion=1] string? b;
+        };
+        """, """\
+        struct S {
+          string a;
+          [MinVersion=1] string? b;
+          [MinVersion=1] string? c;
+        };""")
+
+  def testNewStructFieldWithValidMinVersion(self):
+    """Adding a new field is safe if tagged with a MinVersion greater than any
+    previously used MinVersion in the struct."""
+    self.assertBackwardCompatible(
+        'struct S { int32 a; };',
+        'struct S { int32 a; [MinVersion=1] int32 b; };')
+    self.assertBackwardCompatible(
+        'struct S { int32 a; [MinVersion=1] int32 b; };',
+        'struct S { int32 a; [MinVersion=1] int32 b; [MinVersion=2] bool c; };')
+
+  def testNewStructFieldNullableReference(self):
+    """Adding a new nullable reference-typed field is fine if versioned
+    properly."""
+    self.assertBackwardCompatible(
+        'struct S { int32 a; };',
+        'struct S { int32 a; [MinVersion=1] string? b; };')
+
+  def testStructFieldRename(self):
+    """Renaming a field has no effect on backward-compatibility."""
+    self.assertBackwardCompatible('struct S { int32 x; bool b; };',
+                                  'struct S { int32 a; bool b; };')
+
+  def testStructFieldReorderWithExplicitOrdinals(self):
+    """Reordering fields has no effect on backward-compatibility when field
+    ordinals are explicitly labeled and remain unchanged."""
+    self.assertBackwardCompatible('struct S { bool b@1; int32 a@0; };',
+                                  'struct S { int32 a@0; bool b@1; };')
+
+  def testNewUnionFieldUnversioned(self):
+    """Adding a new field to a union without a new (i.e. higher than any
+    existing version) [MinVersion] tag breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('union U { string a; };',
+                                     'union U { string a; string b; };')
+
+  def testUnionFieldRemoval(self):
+    """Removing a field from a union breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('union U { string a; string b; };',
+                                     'union U { string a; };')
+
+  def testUnionFieldTypeChange(self):
+    """Changing the type of an existing field always breaks
+    backward-compatibility."""
+    self.assertNotBackwardCompatible('union U { string a; };',
+                                     'union U { array<int32> a; };')
+
+  def testUnionFieldBecomingOptional(self):
+    """Changing a field from non-optional to optional breaks
+    backward-compatibility."""
+    self.assertNotBackwardCompatible('union U { string a; };',
+                                     'union U { string? a; };')
+
+  def testFieldNestedTypeChanged(self):
+    """Changing the definition of a nested type within a field (such as an array
+    element or interface endpoint type) should only break backward-compatibility
+    if the changes to that type are not backward-compatible."""
+    self.assertBackwardCompatible(
+        """\
+        struct S { string a; };
+        struct T { array<S> ss; };
+        """, """\
+        struct S {
+          string a;
+          [MinVersion=1] string? b;
+        };
+        struct T { array<S> ss; };
+        """)
+    self.assertBackwardCompatible(
+        """\
+        interface F { Do(); };
+        struct S { pending_receiver<F> r; };
+        """, """\
+        interface F {
+          Do();
+          [MinVersion=1] Say();
+        };
+        struct S { pending_receiver<F> r; };
+        """)
+
+  def testRecursiveTypeChange(self):
+    """Recursive types do not break the compatibility checker."""
+    self.assertBackwardCompatible(
+        """\
+        struct S {
+          string a;
+          array<S> others;
+        };""", """\
+        struct S {
+          string a;
+          array<S> others;
+          [MinVersion=1] string? b;
+        };""")
+
+  def testUnionFieldBecomingNonOptional(self):
+    """Changing a field from optional to non-optional breaks
+    backward-compatibility."""
+    self.assertNotBackwardCompatible('union U { string? a; };',
+                                     'union U { string a; };')
+
+  def testUnionFieldOrderChange(self):
+    """Changing the order of fields breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('union U { string a; bool b; };',
+                                     'union U { bool b; string a; };')
+    self.assertNotBackwardCompatible('union U { string a@0; bool b@1; };',
+                                     'union U { string a@1; bool b@0; };')
+
+  def testUnionFieldMinVersionChange(self):
+    """Changing the MinVersion of a field breaks backward-compatibility."""
+    self.assertNotBackwardCompatible(
+        'union U { string a; [MinVersion=1] string b; };',
+        'union U { string a; [MinVersion=2] string b; };')
+
+  def testUnionFieldTypeChange(self):
+    """If a union field's own type definition changes, the containing union
+    is backward-compatible if and only if the field type's change is
+    backward-compatible."""
+    self.assertBackwardCompatible(
+        'struct S {}; union U { S s; };',
+        'struct S { [MinVersion=1] int32 x; }; union U { S s; };')
+    self.assertBackwardCompatible(
+        '[Extensible] enum E { [Default] kA }; union U { E e; };',
+        """[Extensible] enum E {
+          [Default] kA,
+          [MinVersion=1] kB };
+          union U { E e; };""")
+    self.assertNotBackwardCompatible(
+        'struct S {}; union U { S s; };',
+        'struct S { int32 x; }; union U { S s; };')
+    self.assertNotBackwardCompatible(
+        '[Extensible] enum E { [Default] kA }; union U { E e; };',
+        '[Extensible] enum E { [Default] kA, kB }; union U { E e; };')
+
+  def testNewUnionFieldWithInvalidMinVersion(self):
+    """Adding a new field using an existing MinVersion breaks backward-
+    compatibility."""
+    self.assertNotBackwardCompatible(
+        """\
+        union U {
+          string a;
+          [MinVersion=1] string b;
+        };
+        """, """\
+        union U {
+          string a;
+          [MinVersion=1] string b;
+          [MinVersion=1] string c;
+        };""")
+
+  def testNewUnionFieldWithValidMinVersion(self):
+    """Adding a new field is safe if tagged with a MinVersion greater than any
+    previously used MinVersion in the union."""
+    self.assertBackwardCompatible(
+        'union U { int32 a; };',
+        'union U { int32 a; [MinVersion=1] int32 b; };')
+    self.assertBackwardCompatible(
+        'union U { int32 a; [MinVersion=1] int32 b; };',
+        'union U { int32 a; [MinVersion=1] int32 b; [MinVersion=2] bool c; };')
+
+  def testUnionFieldRename(self):
+    """Renaming a field has no effect on backward-compatibility."""
+    self.assertBackwardCompatible('union U { int32 x; bool b; };',
+                                  'union U { int32 a; bool b; };')
+
+  def testUnionFieldReorderWithExplicitOrdinals(self):
+    """Reordering fields has no effect on backward-compatibility when field
+    ordinals are explicitly labeled and remain unchanged."""
+    self.assertBackwardCompatible('union U { bool b@1; int32 a@0; };',
+                                  'union U { int32 a@0; bool b@1; };')
+
+  def testNewInterfaceMethodUnversioned(self):
+    """Adding a new method to an interface without a new (i.e. higher than any
+    existing version) [MinVersion] tag breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('interface F { A(); };',
+                                     'interface F { A(); B(); };')
+
+  def testInterfaceMethodRemoval(self):
+    """Removing a method from an interface breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('interface F { A(); B(); };',
+                                     'interface F { A(); };')
+
+  def testInterfaceMethodParamsChanged(self):
+    """Changes to the parameter list are only backward-compatible if they meet
+    backward-compatibility requirements of an equivalent struct definition."""
+    self.assertNotBackwardCompatible('interface F { A(); };',
+                                     'interface F { A(int32 x); };')
+    self.assertNotBackwardCompatible('interface F { A(int32 x); };',
+                                     'interface F { A(bool x); };')
+    self.assertNotBackwardCompatible(
+        'interface F { A(int32 x, [MinVersion=1] string? s); };', """\
+        interface F {
+          A(int32 x, [MinVersion=1] string? s, [MinVersion=1] int32 y);
+        };""")
+
+    self.assertBackwardCompatible('interface F { A(int32 x); };',
+                                  'interface F { A(int32 a); };')
+    self.assertBackwardCompatible(
+        'interface F { A(int32 x); };',
+        'interface F { A(int32 x, [MinVersion=1] string? s); };')
+
+    self.assertBackwardCompatible(
+        'struct S {}; interface F { A(S s); };',
+        'struct S { [MinVersion=1] int32 x; }; interface F { A(S s); };')
+    self.assertBackwardCompatible(
+        'struct S {}; struct T {}; interface F { A(S s); };',
+        'struct S {}; struct T {}; interface F { A(T s); };')
+    self.assertNotBackwardCompatible(
+        'struct S {}; struct T { int32 x; }; interface F { A(S s); };',
+        'struct S {}; struct T { int32 x; }; interface F { A(T t); };')
+
+  def testInterfaceMethodReplyAdded(self):
+    """Adding a reply to a message breaks backward-compatibilty."""
+    self.assertNotBackwardCompatible('interface F { A(); };',
+                                     'interface F { A() => (); };')
+
+  def testInterfaceMethodReplyRemoved(self):
+    """Removing a reply from a message breaks backward-compatibility."""
+    self.assertNotBackwardCompatible('interface F { A() => (); };',
+                                     'interface F { A(); };')
+
+  def testInterfaceMethodReplyParamsChanged(self):
+    """Similar to request parameters, a change to reply parameters is considered
+    backward-compatible if it meets the same backward-compatibility
+    requirements imposed on equivalent struct changes."""
+    self.assertNotBackwardCompatible('interface F { A() => (); };',
+                                     'interface F { A() => (int32 x); };')
+    self.assertNotBackwardCompatible('interface F { A() => (int32 x); };',
+                                     'interface F { A() => (); };')
+    self.assertNotBackwardCompatible('interface F { A() => (bool x); };',
+                                     'interface F { A() => (int32 x); };')
+
+    self.assertBackwardCompatible('interface F { A() => (int32 a); };',
+                                  'interface F { A() => (int32 x); };')
+    self.assertBackwardCompatible(
+        'interface F { A() => (int32 x); };',
+        'interface F { A() => (int32 x, [MinVersion] string? s); };')
+
+  def testNewInterfaceMethodWithInvalidMinVersion(self):
+    """Adding a new method to an existing version is not backward-compatible."""
+    self.assertNotBackwardCompatible(
+        """\
+        interface F {
+          A();
+          [MinVersion=1] B();
+        };
+        """, """\
+        interface F {
+          A();
+          [MinVersion=1] B();
+          [MinVersion=1] C();
+        };
+        """)
+
+  def testNewInterfaceMethodWithValidMinVersion(self):
+    """Adding a new method is fine as long as its MinVersion exceeds that of any
+    method on the old interface definition."""
+    self.assertBackwardCompatible('interface F { A(); };',
+                                  'interface F { A(); [MinVersion=1] B(); };')
diff --git a/utils/codegen/ipc/mojo/public/tools/run_all_python_unittests.py b/utils/codegen/ipc/mojo/public/tools/run_all_python_unittests.py
new file mode 100755
index 00000000..98bce18c
--- /dev/null
+++ b/utils/codegen/ipc/mojo/public/tools/run_all_python_unittests.py
@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+# Copyright 2020 The Chromium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os.path
+import sys
+
+_TOOLS_DIR = os.path.dirname(__file__)
+_MOJOM_DIR = os.path.join(_TOOLS_DIR, 'mojom')
+_BINDINGS_DIR = os.path.join(_TOOLS_DIR, 'bindings')
+_SRC_DIR = os.path.join(_TOOLS_DIR, os.path.pardir, os.path.pardir,
+                        os.path.pardir)
+
+# Ensure that the mojom library is discoverable.
+sys.path.append(_MOJOM_DIR)
+sys.path.append(_BINDINGS_DIR)
+
+# Help Python find typ in //third_party/catapult/third_party/typ/
+sys.path.append(
+    os.path.join(_SRC_DIR, 'third_party', 'catapult', 'third_party', 'typ'))
+import typ
+
+
+def Main():
+  return typ.main(top_level_dirs=[_MOJOM_DIR, _BINDINGS_DIR])
+
+
+if __name__ == '__main__':
+  sys.exit(Main())