utils: ipc: Update mojo

Update mojo from commit

9be4263648d7d1a04bb78be75df53f56449a5e3a "Updating trunk VERSION from 6225.0 to 6226.0"

from the Chromium repository.

The update-mojo.sh script was used for this update.

Bug: https://bugs.libcamera.org/show_bug.cgi?id=206
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

23 files changed, 1764 insertions, 719 deletions

diff --git a/utils/ipc/mojo/public/tools/bindings/BUILD.gn b/utils/ipc/mojo/public/tools/bindings/BUILD.gn
index 3e242532..eeca73ea 100644
--- a/utils/ipc/mojo/public/tools/bindings/BUILD.gn
+++ b/utils/ipc/mojo/public/tools/bindings/BUILD.gn
@@ -1,24 +1,27 @@
-# Copyright 2016 The Chromium Authors. All rights reserved.
+# 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("//build/config/python.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//third_party/jinja2/jinja2.gni")
 
-# TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-python2_action("precompile_templates") {
+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",
     "$mojom_generator_root/generators/cpp_templates/module-params-data.h.tmpl",
@@ -26,7 +29,6 @@ python2_action("precompile_templates") {
     "$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",
-    "$mojom_generator_root/generators/cpp_templates/module-test-utils.cc.tmpl",
     "$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",
@@ -65,9 +67,6 @@ python2_action("precompile_templates") {
     "$mojom_generator_root/generators/java_templates/struct.java.tmpl",
     "$mojom_generator_root/generators/java_templates/union.java.tmpl",
     "$mojom_generator_root/generators/js_templates/enum_definition.tmpl",
-    "$mojom_generator_root/generators/js_templates/externs/interface_definition.tmpl",
-    "$mojom_generator_root/generators/js_templates/externs/module.externs.tmpl",
-    "$mojom_generator_root/generators/js_templates/externs/struct_definition.tmpl",
     "$mojom_generator_root/generators/js_templates/fuzzing.tmpl",
     "$mojom_generator_root/generators/js_templates/interface_definition.tmpl",
     "$mojom_generator_root/generators/js_templates/lite/enum_definition.tmpl",
@@ -93,8 +92,11 @@ python2_action("precompile_templates") {
     "$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/mojom.tmpl",
+    "$mojom_generator_root/generators/ts_templates/struct_definition.tmpl",
+    "$mojom_generator_root/generators/ts_templates/union_definition.tmpl",
   ]
   script = mojom_generator_script
 
@@ -102,8 +104,8 @@ python2_action("precompile_templates") {
   outputs = [
     "$target_gen_dir/cpp_templates.zip",
     "$target_gen_dir/java_templates.zip",
-    "$target_gen_dir/mojolpm_templates.zip",
     "$target_gen_dir/js_templates.zip",
+    "$target_gen_dir/mojolpm_templates.zip",
     "$target_gen_dir/ts_templates.zip",
   ]
   args = [
@@ -113,3 +115,17 @@ python2_action("precompile_templates") {
     "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/ipc/mojo/public/tools/bindings/README.md b/utils/ipc/mojo/public/tools/bindings/README.md
index 43882450..b27b2d01 100644
--- a/utils/ipc/mojo/public/tools/bindings/README.md
+++ b/utils/ipc/mojo/public/tools/bindings/README.md
@@ -96,7 +96,7 @@ for message parameters.
 | `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 maping values of type *S* to values of type *T*. *S* may be a `string`, `enum`, or numeric type.
+| `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.
@@ -188,8 +188,8 @@ struct StringPair {
 };
 
 enum AnEnum {
-  YES,
-  NO
+  kYes,
+  kNo
 };
 
 interface SampleInterface {
@@ -209,7 +209,7 @@ struct AllTheThings {
   uint64 unsigned_64bit_value;
   float float_value_32bit;
   double float_value_64bit;
-  AnEnum enum_value = AnEnum.YES;
+  AnEnum enum_value = AnEnum.kYes;
 
   // Strings may be nullable.
   string? maybe_a_string_maybe_not;
@@ -300,14 +300,14 @@ within a module or nested within the namespace of some struct or interface:
 module business.mojom;
 
 enum Department {
-  SALES = 0,
-  DEV,
+  kSales = 0,
+  kDev,
 };
 
 struct Employee {
   enum Type {
-    FULL_TIME,
-    PART_TIME,
+    kFullTime,
+    kPartTime,
   };
 
   Type type;
@@ -315,6 +315,9 @@ struct Employee {
 };
 ```
 
+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.
@@ -336,8 +339,8 @@ struct Employee {
   const uint64 kInvalidId = 0;
 
   enum Type {
-    FULL_TIME,
-    PART_TIME,
+    kFullTime,
+    kPartTime,
   };
 
   uint64 id = kInvalidId;
@@ -348,6 +351,37 @@ struct Employee {
 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
@@ -396,20 +430,33 @@ interesting attributes supported today.
   extreme caution, because it can lead to deadlocks otherwise.
 
 * **`[Default]`**:
-  The `Default` attribute may be used to specify an enumerator value that
-  will be used if an `Extensible` enumeration does not deserialize to a known
-  value on the receiver side, i.e. the sender is using a newer version of the
-  enum. This allows unknown values to be mapped to a well-defined value that can
-  be appropriately handled.
+  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 definition. 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.
+  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.
 
-  Note: in the future, an `Extensible` enumeration will require that a `Default`
-  enumerator value also be specified.
+  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
@@ -422,7 +469,10 @@ interesting attributes supported today.
 * **`[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.
+  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
@@ -442,13 +492,73 @@ interesting attributes supported today.
   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.
+  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
 
@@ -495,9 +605,9 @@ values. For example if a Mojom declares the enum:
 
 ``` cpp
 enum AdvancedBoolean {
-  TRUE = 0,
-  FALSE = 1,
-  FILE_NOT_FOUND = 2,
+  kTrue = 0,
+  kFalse = 1,
+  kFileNotFound = 2,
 };
 ```
 
@@ -550,10 +660,16 @@ See the documentation for
 
 *** note
 **NOTE:** You don't need to worry about versioning if you don't care about
-backwards compatibility. Specifically, all parts of Chrome are updated
-atomically today and there is not yet any possibility of any two Chrome
-processes communicating with two different versions of any given Mojom
-interface.
+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
@@ -593,8 +709,8 @@ struct Employee {
 
 *** note
 **NOTE:** Mojo object or handle types added with a `MinVersion` **MUST** be
-optional (nullable). See [Primitive Types](#Primitive-Types) for details on
-nullable values.
+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
@@ -624,10 +740,10 @@ 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 or *N*-method interface, the set of explicitly
-    assigned ordinal values must be limited to the range *[0, N-1]*. Interfaces
-    should include placeholder methods to fill the ordinal positions of removed
-    methods (for example "Unused_Message_7@7()" or "RemovedMessage@42()", etc).
+* 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
@@ -652,6 +768,24 @@ There are two dimensions on which an interface can be extended
     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.
 
@@ -664,17 +798,12 @@ For example:
 ``` cpp
 // Old version:
 interface HumanResourceDatabase {
-  AddEmployee(Employee employee) => (bool success);
   QueryEmployee(uint64 id) => (Employee? employee);
 };
 
 // New version:
 interface HumanResourceDatabase {
-  AddEmployee(Employee employee) => (bool success);
-
-  QueryEmployee(uint64 id, [MinVersion=1] bool retrieve_finger_print)
-      => (Employee? employee,
-          [MinVersion=1] array<uint8>? finger_print);
+  QueryEmployee(uint64 id) => (Employee? employee);
 
   [MinVersion=1]
   AttachFingerPrint(uint64 id, array<uint8> finger_print)
@@ -682,10 +811,7 @@ interface HumanResourceDatabase {
 };
 ```
 
-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. However, if the method
-call itself is not recognized, it is considered a validation error and the
+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.
@@ -712,8 +838,8 @@ If you want an enum to be extensible in the future, you can apply the
 ``` cpp
 [Extensible]
 enum Department {
-  SALES,
-  DEV,
+  kSales,
+  kDev,
 };
 ```
 
@@ -722,9 +848,9 @@ And later you can extend this enum without breaking backwards compatibility:
 ``` cpp
 [Extensible]
 enum Department {
-  SALES,
-  DEV,
-  [MinVersion=1] RESEARCH,
+  kSales,
+  kDev,
+  [MinVersion=1] kResearch,
 };
 ```
 
@@ -782,7 +908,7 @@ Statement = ModuleStatement | ImportStatement | Definition
 
 ModuleStatement = AttributeSection "module" Identifier ";"
 ImportStatement = "import" StringLiteral ";"
-Definition = Struct Union Interface Enum Const
+Definition = Struct Union Interface Enum Feature Const
 
 AttributeSection = <empty> | "[" AttributeList "]"
 AttributeList = <empty> | NonEmptyAttributeList
@@ -809,7 +935,7 @@ InterfaceBody = <empty>
               | InterfaceBody Const
               | InterfaceBody Enum
               | InterfaceBody Method
-Method = AttributeSection Name Ordinal "(" ParamterList ")" Response ";"
+Method = AttributeSection Name Ordinal "(" ParameterList ")" Response ";"
 ParameterList = <empty> | NonEmptyParameterList
 NonEmptyParameterList = Parameter
                       | Parameter "," NonEmptyParameterList
@@ -847,6 +973,13 @@ 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 ";"
diff --git a/utils/ipc/mojo/public/tools/bindings/checks/__init__.py b/utils/ipc/mojo/public/tools/bindings/checks/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/utils/ipc/mojo/public/tools/bindings/checks/__init__.py
diff --git a/utils/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check.py
new file mode 100644
index 00000000..e6e4f2c9
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check_unittest.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_attributes_check_unittest.py
new file mode 100644
index 00000000..f1a50a4a
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/checks/mojom_definitions_check.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_definitions_check.py
new file mode 100644
index 00000000..702d41c3
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check.py
new file mode 100644
index 00000000..07f51a64
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check_unittest.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_interface_feature_check_unittest.py
new file mode 100644
index 00000000..e96152fd
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_check.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_check.py
new file mode 100644
index 00000000..d570e26c
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_checks_unittest.py b/utils/ipc/mojo/public/tools/bindings/checks/mojom_restrictions_checks_unittest.py
new file mode 100644
index 00000000..a6cd71e2
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/chromium_bindings_configuration.gni b/utils/ipc/mojo/public/tools/bindings/chromium_bindings_configuration.gni
deleted file mode 100644
index d8a13874..00000000
--- a/utils/ipc/mojo/public/tools/bindings/chromium_bindings_configuration.gni
+++ /dev/null
@@ -1,51 +0,0 @@
-# Copyright 2016 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-_typemap_imports = [
-  "//chrome/chrome_cleaner/mojom/typemaps/typemaps.gni",
-  "//chrome/common/importer/typemaps.gni",
-  "//chrome/common/media_router/mojom/typemaps.gni",
-  "//chrome/typemaps.gni",
-  "//chromecast/typemaps.gni",
-  "//chromeos/typemaps.gni",
-  "//chromeos/components/multidevice/mojom/typemaps.gni",
-  "//chromeos/services/cros_healthd/public/mojom/typemaps.gni",
-  "//chromeos/services/device_sync/public/mojom/typemaps.gni",
-  "//chromeos/services/network_config/public/mojom/typemaps.gni",
-  "//chromeos/services/secure_channel/public/mojom/typemaps.gni",
-  "//components/arc/mojom/typemaps.gni",
-  "//components/chromeos_camera/common/typemaps.gni",
-  "//components/services/storage/public/cpp/filesystem/typemaps.gni",
-  "//components/sync/mojom/typemaps.gni",
-  "//components/typemaps.gni",
-  "//content/browser/typemaps.gni",
-  "//content/public/common/typemaps.gni",
-  "//sandbox/mac/mojom/typemaps.gni",
-  "//services/media_session/public/cpp/typemaps.gni",
-  "//services/proxy_resolver/public/cpp/typemaps.gni",
-  "//services/resource_coordinator/public/cpp/typemaps.gni",
-  "//services/service_manager/public/cpp/typemaps.gni",
-  "//services/tracing/public/mojom/typemaps.gni",
-]
-
-_typemaps = []
-foreach(typemap_import, _typemap_imports) {
-  # Avoid reassignment error by assigning to empty scope first.
-  _imported = {
-  }
-  _imported = read_file(typemap_import, "scope")
-  _typemaps += _imported.typemaps
-}
-
-typemaps = []
-foreach(typemap, _typemaps) {
-  typemaps += [
-    {
-      filename = typemap
-      config = read_file(typemap, "scope")
-    },
-  ]
-}
-
-component_macro_suffix = ""
diff --git a/utils/ipc/mojo/public/tools/bindings/compile_typescript.py b/utils/ipc/mojo/public/tools/bindings/compile_typescript.py
deleted file mode 100644
index a978901b..00000000
--- a/utils/ipc/mojo/public/tools/bindings/compile_typescript.py
+++ /dev/null
@@ -1,27 +0,0 @@
-# Copyright 2019 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-import os
-import sys
-import argparse
-
-_HERE_PATH = os.path.dirname(__file__)
-_SRC_PATH = os.path.normpath(os.path.join(_HERE_PATH, '..', '..', '..', '..'))
-
-sys.path.append(os.path.join(_SRC_PATH, 'third_party', 'node'))
-import node
-import node_modules
-
-def main(argv):
-  parser = argparse.ArgumentParser()
-  parser.add_argument('--tsconfig_path', required=True)
-  args = parser.parse_args(argv)
-
-  result = node.RunNode([node_modules.PathToTypescript()] +
-                        ['--project', args.tsconfig_path])
-  if len(result) != 0:
-    raise RuntimeError('Failed to compile Typescript: \n%s' % result)
-
-if __name__ == '__main__':
-  main(sys.argv[1:])
diff --git a/utils/ipc/mojo/public/tools/bindings/concatenate-files.py b/utils/ipc/mojo/public/tools/bindings/concatenate-files.py
index 48bc66fd..4dd26d4a 100755
--- a/utils/ipc/mojo/public/tools/bindings/concatenate-files.py
+++ b/utils/ipc/mojo/public/tools/bindings/concatenate-files.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright 2019 The Chromium Authors. All rights reserved.
+# 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.
 #
@@ -15,6 +15,7 @@
 from __future__ import print_function
 
 import optparse
+import sys
 
 
 def Concatenate(filenames):
@@ -47,7 +48,7 @@ def main():
   parser.set_usage("""Concatenate several files into one.
       Equivalent to: cat file1 ... > target.""")
   (_options, args) = parser.parse_args()
-  exit(0 if Concatenate(args) else 1)
+  sys.exit(0 if Concatenate(args) else 1)
 
 
 if __name__ == "__main__":
diff --git a/utils/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py b/utils/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py
index be8985ce..7d56c9f9 100755
--- a/utils/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py
+++ b/utils/ipc/mojo/public/tools/bindings/concatenate_and_replace_closure_exports.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright 2018 The Chromium Authors. All rights reserved.
+# 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.
 
@@ -20,6 +20,7 @@ from __future__ import print_function
 
 import optparse
 import re
+import sys
 
 
 _MOJO_INTERNAL_MODULE_NAME = "mojo.internal"
@@ -31,10 +32,10 @@ def FilterLine(filename, line, output):
     return
 
   if line.startswith("goog.provide"):
-    match = re.match("goog.provide\('([^']+)'\);", line)
+    match = re.match(r"goog.provide\('([^']+)'\);", line)
     if not match:
       print("Invalid goog.provide line in %s:\n%s" % (filename, line))
-      exit(1)
+      sys.exit(1)
 
     module_name = match.group(1)
     if module_name == _MOJO_INTERNAL_MODULE_NAME:
@@ -67,7 +68,8 @@ def main():
     Concatenate several files into one, stripping Closure provide and
     require directives along the way.""")
   (_, args) = parser.parse_args()
-  exit(0 if ConcatenateAndReplaceExports(args) else 1)
+  sys.exit(0 if ConcatenateAndReplaceExports(args) else 1)
+
 
 if __name__ == "__main__":
   main()
diff --git a/utils/ipc/mojo/public/tools/bindings/format_typemap_generator_args.py b/utils/ipc/mojo/public/tools/bindings/format_typemap_generator_args.py
deleted file mode 100755
index 7ac4af5f..00000000
--- a/utils/ipc/mojo/public/tools/bindings/format_typemap_generator_args.py
+++ /dev/null
@@ -1,36 +0,0 @@
-#!/usr/bin/env python
-# Copyright 2016 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-from __future__ import print_function
-
-import sys
-
-# This utility converts mojom dependencies into their corresponding typemap
-# paths and formats them to be consumed by generate_type_mappings.py.
-
-
-def FormatTypemap(typemap_filename):
-  # A simple typemap is valid Python with a minor alteration.
-  with open(typemap_filename) as f:
-    typemap_content = f.read().replace('=\n', '=')
-  typemap = {}
-  exec typemap_content in typemap
-
-  for header in typemap.get('public_headers', []):
-    yield 'public_headers=%s' % header
-  for header in typemap.get('traits_headers', []):
-    yield 'traits_headers=%s' % header
-  for header in typemap.get('type_mappings', []):
-    yield 'type_mappings=%s' % header
-
-
-def main():
-  typemaps = sys.argv[1:]
-  print(' '.join('--start-typemap %s' % ' '.join(FormatTypemap(typemap))
-                 for typemap in typemaps))
-
-
-if __name__ == '__main__':
-  sys.exit(main())
diff --git a/utils/ipc/mojo/public/tools/bindings/gen_data_files_list.py b/utils/ipc/mojo/public/tools/bindings/gen_data_files_list.py
index 8b78d092..c6daff03 100644
--- a/utils/ipc/mojo/public/tools/bindings/gen_data_files_list.py
+++ b/utils/ipc/mojo/public/tools/bindings/gen_data_files_list.py
@@ -1,4 +1,4 @@
-# Copyright 2017 The Chromium Authors. All rights reserved.
+# 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.
diff --git a/utils/ipc/mojo/public/tools/bindings/generate_type_mappings.py b/utils/ipc/mojo/public/tools/bindings/generate_type_mappings.py
index a0096649..4a53e2bf 100755
--- a/utils/ipc/mojo/public/tools/bindings/generate_type_mappings.py
+++ b/utils/ipc/mojo/public/tools/bindings/generate_type_mappings.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright 2016 The Chromium Authors. All rights reserved.
+# 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.
@@ -82,10 +82,12 @@ def LoadCppTypemapConfig(path):
       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),
diff --git a/utils/ipc/mojo/public/tools/bindings/minify_with_terser.py b/utils/ipc/mojo/public/tools/bindings/minify_with_terser.py
new file mode 100755
index 00000000..cefee7a4
--- /dev/null
+++ b/utils/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/ipc/mojo/public/tools/bindings/mojom.gni b/utils/ipc/mojo/public/tools/bindings/mojom.gni
index fe2a1da3..3f6e54e0 100644
--- a/utils/ipc/mojo/public/tools/bindings/mojom.gni
+++ b/utils/ipc/mojo/public/tools/bindings/mojom.gni
@@ -1,25 +1,28 @@
-# Copyright 2014 The Chromium Authors. All rights reserved.
+# 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("//build/config/python.gni")
 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/chromecast_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
@@ -34,21 +37,30 @@ declare_args() {
 
   # 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. Set to |false| to disable message ID
-  # scrambling on all platforms.
-  enable_mojom_message_id_scrambling = true
+  # 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.
-  enable_mojom_closure_compile = enable_js_type_check && optimize_webui
-
-  # Enables generating Typescript bindings and compiling them to JS bindings.
-  enable_typescript_bindings = false
+  if (is_chromeos_ash) {
+    enable_mojom_closure_compile = enable_js_type_check && optimize_webui
+  }
+}
 
-  # Enables generating javascript fuzzing-related code and the bindings for the
-  # MojoLPM fuzzer targets. Off by default.
-  enable_mojom_fuzzer = false
+# 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
@@ -69,9 +81,8 @@ declare_args() {
 # lacros-chrome switches to target_os="chromeos"
 enable_scrambled_message_ids =
     enable_mojom_message_id_scrambling &&
-    (is_mac || is_win ||
-     (is_linux && !is_chromeos_ash && !is_chromecast && !is_chromeos_lacros) ||
-     ((enable_nacl || is_nacl || is_nacl_nonsfi) &&
+    (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"
@@ -80,7 +91,9 @@ 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",
   "$_mojom_library_root/generate/pack.py",
@@ -88,21 +101,32 @@ mojom_parser_sources = [
   "$_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_mojolpm_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) {
@@ -243,12 +267,16 @@ if (enable_scrambled_message_ids) {
 #       |cpp_only| is set to true, it overrides this to prevent generation of
 #       Java bindings.
 #
-#   enable_fuzzing (optional)
+#   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|. If
-#       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.
+#       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
@@ -310,8 +338,15 @@ if (enable_scrambled_message_ids) {
 #       correct dependency order. Note that this only has an effect if
 #       the |enable_mojom_closure_compile| global arg is set to |true| as well.
 #
-#   use_typescript_sources (optional)
-#       Uses the Typescript generator to generate JavaScript bindings.
+#   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.
@@ -323,17 +358,23 @@ if (enable_scrambled_message_ids) {
 #   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".
+#       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 manually packaged and mapped independently by that page's
-#       WebUIDataSource. The mapped path must match the path given here.
+#       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 generated resources must be added to
-#       content_resources.grd and registered with
-#       content::SharedResourcesDataSource with a corresponding path, at which
-#       point they will be made available to all WebUI pages at the given URL.
+#       "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
@@ -402,16 +443,41 @@ if (enable_scrambled_message_ids) {
 #             should be mapped in generated bindings. This is a string like
 #             "::base::Value" or "std::vector<::base::Value>".
 #
-#         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.
-#
 #         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
@@ -421,16 +487,6 @@ if (enable_scrambled_message_ids) {
 #             type with absl::optional, and null values are simply
 #             absl::nullopt.
 #
-#         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).
-#
-#         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.
-#
 # Additional typemap scope parameters:
 #
 #   traits_headers (optional)
@@ -621,20 +677,26 @@ template("mojom") {
   build_metadata_filename = "$target_gen_dir/$target_name.build_metadata"
   build_metadata = {
   }
-  build_metadata.sources = rebase_path(sources_list)
+  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") ]
+        [ rebase_path("$dep_target_gen_dir/$dep_name.build_metadata",
+                      target_gen_dir) ]
   }
   write_file(build_metadata_filename, build_metadata, "json")
 
-  generate_fuzzing =
-      (!defined(invoker.enable_fuzzing) || invoker.enable_fuzzing) &&
+  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) {
@@ -665,30 +727,34 @@ template("mojom") {
         "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 || is_chromeos_lacros) {
+    } else if (is_linux) {
       enabled_features += [ "is_linux" ]
-      if (is_chromeos_lacros) {
-        enabled_features += [
-          "is_chromeos",
-          "is_chromeos_lacros",
-        ]
-      }
     } else if (is_mac) {
       enabled_features += [ "is_mac" ]
     } else if (is_win) {
       enabled_features += [ "is_win" ]
     }
 
-    # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-    python2_action(parser_target_name) {
+    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 + [ build_metadata_filename ]
+      inputs = mojom_parser_sources + ply_sources + [ build_metadata_filename ]
       sources = sources_list
-      deps = parser_deps
+      public_deps = parser_deps
       outputs = []
       foreach(base_path, output_file_base_paths) {
         filename = get_path_info(base_path, "file")
@@ -698,31 +764,35 @@ template("mojom") {
 
       filelist = []
       foreach(source, sources_list) {
-        filelist += [ rebase_path(source) ]
+        filelist += [ rebase_path(source, root_build_dir) ]
       }
-      response_file_contents = filelist
+
+      # 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("//."),
+        rebase_path("//.", root_build_dir),
         "--input-root",
-        rebase_path(root_gen_dir),
+        rebase_path(root_gen_dir, root_build_dir),
 
         "--output-root",
-        rebase_path(root_gen_dir),
+        rebase_path(root_gen_dir, root_build_dir),
 
-        "--mojom-file-list={{response_file_name}}",
+        "--mojom-file-list=" + rebase_path(rsp_file, root_build_dir),
 
         "--check-imports",
-        rebase_path(build_metadata_filename),
+        rebase_path(build_metadata_filename, root_build_dir),
       ]
 
       if (defined(invoker.input_root_override)) {
         args += [
           "--input-root",
-          rebase_path(invoker.input_root_override),
+          rebase_path(invoker.input_root_override, root_build_dir),
         ]
       }
 
@@ -738,6 +808,13 @@ template("mojom") {
           "--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",
+          ]
+        }
       }
     }
   }
@@ -819,11 +896,12 @@ template("mojom") {
       }
     }
 
-    # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-    python2_action(generator_cpp_message_ids_target_name) {
+    action(generator_cpp_message_ids_target_name) {
+      allow_remote = true
       script = mojom_generator_script
       inputs = mojom_generator_sources + jinja2_sources
-      sources = sources_list
+      sources = sources_list +
+                [ "$root_gen_dir/mojo/public/tools/bindings/cpp_templates.zip" ]
       deps = [
         ":$parser_target_name",
         "//mojo/public/tools/bindings:precompile_templates",
@@ -835,16 +913,22 @@ template("mojom") {
       args = common_generator_args
       filelist = []
       foreach(source, sources_list) {
-        filelist += [ rebase_path("$source", root_build_dir) ]
+        filelist += [ rebase_path(source, root_build_dir) ]
       }
       foreach(base_path, output_file_base_paths) {
+        filename = get_path_info(base_path, "file")
+        dirname = get_path_info(base_path, "dir")
+        inputs += [ "$root_gen_dir/$dirname/${filename}-module" ]
         outputs += [ "$root_gen_dir/$base_path-shared-message-ids.h" ]
       }
 
-      response_file_contents = filelist
+      # 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={{response_file_name}}",
+        "--filelist=" + rebase_path(rsp_file, root_build_dir),
         "--generate_non_variant_code",
         "--generate_message_ids",
         "-g",
@@ -860,12 +944,13 @@ template("mojom") {
 
     generator_shared_target_name = "${target_name}_shared__generator"
 
-    # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-    python2_action(generator_shared_target_name) {
+    action(generator_shared_target_name) {
+      allow_remote = true
       visibility = [ ":*" ]
       script = mojom_generator_script
       inputs = mojom_generator_sources + jinja2_sources
-      sources = sources_list
+      sources = sources_list +
+                [ "$root_gen_dir/mojo/public/tools/bindings/cpp_templates.zip" ]
       deps = [
         ":$parser_target_name",
         "//mojo/public/tools/bindings:precompile_templates",
@@ -878,10 +963,16 @@ template("mojom") {
       args = common_generator_args
       filelist = []
       foreach(source, sources_list) {
-        filelist += [ rebase_path("$source", root_build_dir) ]
+        filelist += [ rebase_path(source, root_build_dir) ]
       }
       foreach(base_path, output_file_base_paths) {
+        # Need the mojom-module as an input to this action.
+        filename = get_path_info(base_path, "file")
+        dirname = get_path_info(base_path, "dir")
+        inputs += [ "$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",
@@ -889,10 +980,13 @@ template("mojom") {
         ]
       }
 
-      response_file_contents = filelist
+      # 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={{response_file_name}}",
+        "--filelist=" + rebase_path(rsp_file, root_build_dir),
         "--generate_non_variant_code",
         "-g",
         "c++",
@@ -923,12 +1017,14 @@ template("mojom") {
     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",
@@ -972,7 +1068,7 @@ template("mojom") {
     }
   }
 
-  if (generate_fuzzing) {
+  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
@@ -981,11 +1077,15 @@ template("mojom") {
     generator_mojolpm_proto_target_name =
         "${target_name}_mojolpm_proto_generator"
 
-    # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-    python2_action(generator_mojolpm_proto_target_name) {
+    action(generator_mojolpm_proto_target_name) {
+      allow_remote = true
       script = mojom_generator_script
       inputs = mojom_generator_sources + jinja2_sources
-      sources = invoker.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 = [
         ":$parser_target_name",
         "//mojo/public/tools/bindings:precompile_templates",
@@ -994,15 +1094,37 @@ template("mojom") {
       outputs = []
       args = common_generator_args
       filelist = []
-      foreach(source, invoker.sources) {
-        filelist += [ rebase_path("$source", root_build_dir) ]
+
+      # 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" ]
       }
 
-      response_file_contents = filelist
+      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={{response_file_name}}",
+        "--filelist=" + rebase_path(rsp_file, root_build_dir),
         "--generate_non_variant_code",
         "-g",
         "mojolpm",
@@ -1014,9 +1136,20 @@ template("mojom") {
       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(
-                invoker.sources,
+                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 = "${root_gen_dir}"
         proto_out_dir = "."
@@ -1055,7 +1188,7 @@ template("mojom") {
     component_macro_suffix = ""
   }
   if ((!defined(invoker.disable_variants) || !invoker.disable_variants) &&
-      !is_ios) {
+      use_blink) {
     blink_variant = {
       variant = "blink"
       component_macro_suffix = "_BLINK"
@@ -1149,39 +1282,6 @@ template("mojom") {
             "${bindings_configuration.component_macro_suffix}_IMPL" ]
     }
 
-    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",
-      ]
-    }
-
     generate_java = false
     if (!cpp_only && defined(invoker.generate_java)) {
       generate_java = invoker.generate_java
@@ -1190,6 +1290,38 @@ template("mojom") {
     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}" +
+              "${bindings_configuration.component_macro_suffix})",
+          "--export_header",
+          "base/component_export.h",
+        ]
+      }
+
       generator_cpp_output_suffixes = []
       variant_dash_suffix = ""
       if (defined(variant)) {
@@ -1198,7 +1330,6 @@ template("mojom") {
       generator_cpp_output_suffixes += [
         "${variant_dash_suffix}-forward.h",
         "${variant_dash_suffix}-import-headers.h",
-        "${variant_dash_suffix}-test-utils.cc",
         "${variant_dash_suffix}-test-utils.h",
         "${variant_dash_suffix}.cc",
         "${variant_dash_suffix}.h",
@@ -1207,16 +1338,28 @@ template("mojom") {
       generator_target_name = "${target_name}${variant_suffix}__generator"
 
       # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-      python2_action(generator_target_name) {
+      action(generator_target_name) {
+        allow_remote = true
         visibility = [ ":*" ]
         script = mojom_generator_script
         inputs = mojom_generator_sources + jinja2_sources
-        sources = sources_list
+        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
         }
@@ -1224,18 +1367,22 @@ template("mojom") {
         args = common_generator_args + export_args
         filelist = []
         foreach(source, sources_list) {
-          filelist += [ rebase_path("$source", root_build_dir) ]
+          filelist += [ rebase_path(source, root_build_dir) ]
         }
         foreach(base_path, output_file_base_paths) {
+          filename = get_path_info(base_path, "file")
+          dirname = get_path_info(base_path, "dir")
+          inputs += [ "$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}${variant_dash_suffix}-test-utils.cc",
             "$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_fuzzing && !defined(bindings_configuration.variant)) {
+          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",
@@ -1243,14 +1390,17 @@ template("mojom") {
           }
         }
 
-        response_file_contents = filelist
-
+        # 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={{response_file_name}}",
+          "--filelist=" + rebase_path("$rsp_file", root_build_dir),
           "-g",
         ]
 
-        if (generate_fuzzing && !defined(bindings_configuration.variant)) {
+        if (generate_mojolpm_fuzzing &&
+            !defined(bindings_configuration.variant)) {
           args += [ "c++,mojolpm" ]
         } else {
           args += [ "c++" ]
@@ -1294,6 +1444,8 @@ template("mojom") {
               "--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")
@@ -1306,62 +1458,6 @@ template("mojom") {
       }
     }
 
-    if (generate_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)) {
-          sources = process_file_template(
-                  invoker.sources,
-                  [
-                    "{{source_gen_dir}}/{{source_file_part}}-mojolpm.cc",
-                    "{{source_gen_dir}}/{{source_file_part}}-mojolpm.h",
-                  ])
-          deps = []
-        } 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
-          }
-        }
-      }
-    }
-
     # 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.
@@ -1389,20 +1485,20 @@ template("mojom") {
     write_file(_typemap_config_filename, _rebased_typemap_configs, "json")
     _mojom_target_name = target_name
 
-    # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-    python2_action(_typemap_validator_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),
-        rebase_path(_typemap_stamp_filename),
+        rebase_path(_typemap_config_filename, root_build_dir),
+        rebase_path(_typemap_stamp_filename, root_build_dir),
       ]
     }
 
-    # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-    python2_action(type_mappings_target_name) {
+    action(type_mappings_target_name) {
+      allow_remote = true
       inputs =
           mojom_generator_sources + jinja2_sources + [ _typemap_stamp_filename ]
       outputs = [ type_mappings_path ]
@@ -1413,6 +1509,7 @@ template("mojom") {
         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")
@@ -1422,12 +1519,11 @@ template("mojom") {
         dependency_output_dir =
             get_label_info(dependency_output, "target_gen_dir")
         dependency_name = get_label_info(dependency_output, "name")
-        dependency_path =
-            rebase_path("$dependency_output_dir/${dependency_name}",
-                        root_build_dir)
+        dependency_path = "$dependency_output_dir/${dependency_name}"
+        sources += [ dependency_path ]
         args += [
           "--dependency",
-          dependency_path,
+          rebase_path(dependency_path, root_build_dir),
         ]
       }
 
@@ -1485,11 +1581,15 @@ template("mojom") {
       if (defined(output_name_override)) {
         output_name = output_name_override
       }
-      visibility = output_visibility + [ ":$output_target_name" ]
+      visibility = output_visibility + [
+                     ":$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 = []
@@ -1578,13 +1678,81 @@ template("mojom") {
       }
     }
 
+    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 != []) {
-        # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-        python2_action(java_generator_target_name) {
+        action(java_generator_target_name) {
           script = mojom_generator_script
           inputs = mojom_generator_sources + jinja2_sources
           sources = sources_list
@@ -1597,7 +1765,7 @@ template("mojom") {
           args = common_generator_args
           filelist = []
           foreach(source, sources_list) {
-            filelist += [ rebase_path("$source", root_build_dir) ]
+            filelist += [ rebase_path(source, root_build_dir) ]
           }
           foreach(base_path, output_file_base_paths) {
             outputs += [ "$root_gen_dir/$base_path.srcjar" ]
@@ -1624,8 +1792,7 @@ template("mojom") {
 
       java_srcjar_target_name = target_name + "_java_sources"
 
-      # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-      python2_action(java_srcjar_target_name) {
+      action(java_srcjar_target_name) {
         script = "//build/android/gyp/zip.py"
         inputs = []
         if (output_file_base_paths != []) {
@@ -1651,7 +1818,6 @@ template("mojom") {
       android_library(java_target_name) {
         forward_variables_from(invoker, [ "enable_bytecode_checks" ])
         deps = [
-          "//base:base_java",
           "//mojo/public/java:bindings_java",
           "//mojo/public/java:system_java",
           "//third_party/androidx:androidx_annotation_annotation_java",
@@ -1673,21 +1839,36 @@ template("mojom") {
     }
   }
 
-  use_typescript_for_target =
-      enable_typescript_bindings && defined(invoker.use_typescript_sources) &&
-      invoker.use_typescript_sources
+  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)
 
-  if (!use_typescript_for_target && defined(invoker.use_typescript_sources)) {
-    not_needed(invoker, [ "use_typescript_sources" ])
+  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" ])
   }
 
-  if ((generate_fuzzing || !defined(invoker.cpp_only) || !invoker.cpp_only) &&
-      !use_typescript_for_target) {
+  # 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"
 
-      # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-      python2_action(generator_js_target_name) {
+      action(generator_js_target_name) {
         script = mojom_generator_script
         inputs = mojom_generator_sources + jinja2_sources
         sources = sources_list
@@ -1702,19 +1883,18 @@ template("mojom") {
         args = common_generator_args
         filelist = []
         foreach(source, sources_list) {
-          filelist += [ rebase_path("$source", root_build_dir) ]
+          filelist += [ rebase_path(source, root_build_dir) ]
         }
         foreach(base_path, output_file_base_paths) {
           outputs += [
             "$root_gen_dir/$base_path.js",
-            "$root_gen_dir/$base_path.externs.js",
             "$root_gen_dir/$base_path.m.js",
             "$root_gen_dir/$base_path-lite.js",
-            "$root_gen_dir/$base_path.html",
             "$root_gen_dir/$base_path-lite-for-compile.js",
           ]
 
-          if (defined(invoker.webui_module_path)) {
+          if (defined(invoker.webui_module_path) &&
+              !use_typescript_for_target) {
             outputs += [ "$root_gen_dir/mojom-webui/$base_path-webui.js" ]
           }
         }
@@ -1725,7 +1905,6 @@ template("mojom") {
           "--filelist={{response_file_name}}",
           "-g",
           "javascript",
-          "--js_bindings_mode=new",
         ]
 
         if (defined(invoker.js_generate_struct_deserializers) &&
@@ -1739,7 +1918,7 @@ template("mojom") {
           args += message_scrambling_args
         }
 
-        if (generate_fuzzing) {
+        if (generate_js_fuzzing) {
           args += [ "--generate_fuzzing" ]
         }
       }
@@ -1783,31 +1962,13 @@ template("mojom") {
         data_deps += [ "${full_name}_js_data_deps" ]
       }
     }
+  }
 
-    js_library_target_name = "${target_name}_js_library"
-    if (sources_list != []) {
-      js_library(js_library_target_name) {
-        extra_public_deps = [ ":$generator_js_target_name" ]
-        sources = []
-        foreach(base_path, output_file_base_paths) {
-          sources += [ "$root_gen_dir/${base_path}-lite.js" ]
-        }
-        externs_list = [
-          "${externs_path}/mojo_core.js",
-          "${externs_path}/pending.js",
-        ]
-
-        deps = []
-        foreach(d, all_deps) {
-          full_name = get_label_info(d, "label_no_toolchain")
-          deps += [ "${full_name}_js_library" ]
-        }
-      }
-    } else {
-      group(js_library_target_name) {
-      }
-    }
-
+  # js_library() closure compiler targets, primarily used on ChromeOS. Only
+  # generate these targets if the mojom target is not C++ only and is not using
+  # TypeScript.
+  if (generate_mojom_closure_libraries &&
+      (!defined(invoker.cpp_only) || !invoker.cpp_only) && generate_legacy_js) {
     js_library_for_compile_target_name = "${target_name}_js_library_for_compile"
     if (sources_list != []) {
       js_library(js_library_for_compile_target_name) {
@@ -1834,35 +1995,9 @@ template("mojom") {
       }
     }
 
-    js_modules_target_name = "${target_name}_js_modules"
-    if (sources_list != []) {
-      js_library(js_modules_target_name) {
-        extra_public_deps = [ ":$generator_js_target_name" ]
-        sources = []
-        foreach(base_path, output_file_base_paths) {
-          sources += [ "$root_gen_dir/${base_path}.m.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 += [ "${full_name}_js_modules" ]
-        }
-      }
-    } else {
-      group(js_modules_target_name) {
-      }
-    }
-
-    if (defined(invoker.webui_module_path)) {
+    # WebUI specific closure targets, not needed by targets that are generating
+    # TypeScript WebUI bindings or by legacy-only targets.
+    if (defined(invoker.webui_module_path) && !use_typescript_for_target) {
       webui_js_target_name = "${target_name}_webui_js"
       if (sources_list != []) {
         js_library(webui_js_target_name) {
@@ -1890,46 +2025,38 @@ template("mojom") {
         group(webui_js_target_name) {
         }
       }
-    }
-  }
-  if ((generate_fuzzing || !defined(invoker.cpp_only) || !invoker.cpp_only) &&
-      use_typescript_for_target) {
-    generator_js_target_names = []
-    source_filelist = []
-    foreach(source, sources_list) {
-      source_filelist += [ rebase_path("$source", root_build_dir) ]
-    }
 
-    dependency_types = [
-      {
-        name = "regular"
-        ts_extension = ".ts"
-        js_extension = ".js"
-      },
-      {
-        name = "es_modules"
-        ts_extension = ".m.ts"
-        js_extension = ".m.js"
-      },
-    ]
+      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
 
-    foreach(dependency_type, dependency_types) {
-      ts_outputs = []
-      js_outputs = []
+        deps = [ ":$webui_js_target_name" ]
 
-      foreach(base_path, output_file_base_paths) {
-        ts_outputs +=
-            [ "$root_gen_dir/$base_path-lite${dependency_type.ts_extension}" ]
-        js_outputs +=
-            [ "$root_gen_dir/$base_path-lite${dependency_type.js_extension}" ]
+        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 =
-          "${target_name}_${dependency_type.name}__ts__generator"
+      generator_ts_target_name = "${target_name}_ts__generator"
 
-      # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-      python2_action(generator_ts_target_name) {
+      action(generator_ts_target_name) {
         script = mojom_generator_script
         inputs = mojom_generator_sources + jinja2_sources
         sources = sources_list
@@ -1938,7 +2065,10 @@ template("mojom") {
           "//mojo/public/tools/bindings:precompile_templates",
         ]
 
-        outputs = ts_outputs
+        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
 
@@ -1948,97 +2078,20 @@ template("mojom") {
           "typescript",
         ]
 
-        if (dependency_type.name == "es_modules") {
-          args += [ "--ts_use_es_modules" ]
-        }
-
-        # TODO(crbug.com/1007587): Support scramble_message_ids.
-        # TODO(crbug.com/1007591): Support generate_fuzzing.
-      }
-
-      # Create tsconfig.json for the generated Typescript.
-      tsconfig_filename =
-          "$target_gen_dir/$target_name-${dependency_type.name}-tsconfig.json"
-      tsconfig = {
-      }
-      tsconfig.compilerOptions = {
-        composite = true
-        target = "es6"
-        module = "es6"
-        lib = [
-          "es6",
-          "esnext.bigint",
-        ]
-        strict = true
-      }
-      tsconfig.files = []
-      foreach(base_path, output_file_base_paths) {
-        tsconfig.files += [ rebase_path(
-                "$root_gen_dir/$base_path-lite${dependency_type.ts_extension}",
-                target_gen_dir,
-                root_gen_dir) ]
-      }
-      tsconfig.references = []
-
-      # Get tsconfigs for deps.
-      foreach(d, all_deps) {
-        dep_target_gen_dir = rebase_path(get_label_info(d, "target_gen_dir"))
-        dep_name = get_label_info(d, "name")
-        reference = {
-        }
-        reference.path = "$dep_target_gen_dir/$dep_name-${dependency_type.name}-tsconfig.json"
-        tsconfig.references += [ reference ]
-      }
-      write_file(tsconfig_filename, tsconfig, "json")
-
-      # Compile previously generated Typescript to Javascript.
-      generator_js_target_name =
-          "${target_name}_${dependency_type.name}__js__generator"
-      generator_js_target_names += [ generator_js_target_name ]
-
-      # TODO(crbug.com/1194274): Investigate nondeterminism in Py3 builds.
-      python2_action(generator_js_target_name) {
-        script = "$mojom_generator_root/compile_typescript.py"
-        sources = ts_outputs
-        outputs = js_outputs
-        public_deps = [ ":$generator_ts_target_name" ]
-        foreach(d, all_deps) {
-          full_name = get_label_info(d, "label_no_toolchain")
-          public_deps +=
-              [ "${full_name}_${dependency_type.name}__js__generator" ]
+        if (!defined(invoker.scramble_message_ids) ||
+            invoker.scramble_message_ids) {
+          inputs += message_scrambling_inputs
+          args += message_scrambling_args
         }
 
-        absolute_tsconfig_path =
-            rebase_path(tsconfig_filename, "", target_gen_dir)
-        args = [ "--tsconfig_path=$absolute_tsconfig_path" ]
-      }
-    }
-
-    js_target_name = target_name + "_js"
-    group(js_target_name) {
-      public_deps = []
-      if (sources_list != []) {
-        foreach(generator_js_target_name, generator_js_target_names) {
-          public_deps += [ ":$generator_js_target_name" ]
+        if (defined(invoker.js_generate_struct_deserializers) &&
+            invoker.js_generate_struct_deserializers) {
+          args += [ "--js_generate_struct_deserializers" ]
         }
-      }
 
-      foreach(d, all_deps) {
-        full_name = get_label_info(d, "label_no_toolchain")
-        public_deps += [ "${full_name}_js" ]
-      }
-    }
-
-    group(js_data_deps_target_name) {
-      data = js_outputs
-      deps = []
-      foreach(generator_js_target_name, generator_js_target_names) {
-        deps += [ ":$generator_js_target_name" ]
-      }
-      data_deps = []
-      foreach(d, all_deps) {
-        full_name = get_label_info(d, "label_no_toolchain")
-        data_deps += [ "${full_name}_js_data_deps" ]
+        # TODO(crbug.com/1007587): Support scramble_message_ids if above is
+        # insufficient.
+        # TODO(crbug.com/1007591): Support generate_fuzzing.
       }
     }
   }
diff --git a/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py b/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py
index da9efc71..8c641c2a 100755
--- a/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py
+++ b/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright 2013 The Chromium Authors. All rights reserved.
+# 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.
 
@@ -57,10 +57,17 @@ _BUILTIN_GENERATORS = {
     "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.
+    return {}  # No generators.
 
   generators = {}
   for generator_name in [s.strip() for s in generators_string.split(",")]:
@@ -74,6 +81,21 @@ def LoadGenerators(generators_string):
   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.)"""
@@ -82,7 +104,7 @@ def MakeImportStackMessage(imported_filename_stack):
                     zip(imported_filename_stack[1:], imported_filename_stack)]))
 
 
-class RelativePath(object):
+class RelativePath:
   """Represents a path relative to the source tree or generated output dir."""
 
   def __init__(self, path, source_root, output_dir):
@@ -142,7 +164,7 @@ def ReadFileContents(filename):
     return f.read()
 
 
-class MojomProcessor(object):
+class MojomProcessor:
   """Takes parsed mojom modules and generates language bindings from them.
 
   Attributes:
@@ -169,8 +191,8 @@ class MojomProcessor(object):
     if 'c++' in self._typemap:
       self._typemap['mojolpm'] = self._typemap['c++']
 
-  def _GenerateModule(self, args, remaining_args, generator_modules,
-                      rel_filename, imported_filename_stack):
+  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]
@@ -190,12 +212,16 @@ class MojomProcessor(object):
       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_bindings_mode=args.js_bindings_mode,
             js_generate_struct_deserializers=\
                     args.js_generate_struct_deserializers,
             export_attribute=args.export_attribute,
@@ -234,6 +260,7 @@ def _Generate(args, remaining_args):
       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)
 
@@ -246,7 +273,7 @@ def _Generate(args, remaining_args):
 
   for filename in args.filename:
     processor._GenerateModule(
-        args, remaining_args, generator_modules,
+        args, remaining_args, check_modules, generator_modules,
         RelativePath(filename, args.depth, args.output_dir), [])
 
   return 0
@@ -286,6 +313,12 @@ def main():
                                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.")
@@ -309,11 +342,6 @@ def main():
                                help="Use WTF types as generated types for mojo "
                                "string/array/map.")
   generate_parser.add_argument(
-      "--js_bindings_mode", choices=["new", "old"], default="old",
-      help="This option only affects the JavaScript bindings. The value could "
-      "be \"new\" to generate new-style lite JS bindings in addition to the "
-      "old, or \"old\" to only generate old bindings.")
-  generate_parser.add_argument(
       "--js_generate_struct_deserializers", action="store_true",
       help="Generate javascript deserialize methods for structs in "
       "mojom-lite.js file")
@@ -387,4 +415,10 @@ def main():
 
 if __name__ == "__main__":
   with crbug_1001171.DumpStateOnLookupError():
-    sys.exit(main())
+    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/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py b/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py
index bddbe3f4..761922b6 100644
--- a/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py
+++ b/utils/ipc/mojo/public/tools/bindings/mojom_bindings_generator_unittest.py
@@ -1,4 +1,4 @@
-# Copyright 2014 The Chromium Authors. All rights reserved.
+# 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.
 
@@ -8,13 +8,13 @@ from mojom_bindings_generator import MakeImportStackMessage
 from mojom_bindings_generator import ScrambleMethodOrdinals
 
 
-class FakeIface(object):
+class FakeIface:
   def __init__(self):
     self.mojom_name = None
     self.methods = None
 
 
-class FakeMethod(object):
+class FakeMethod:
   def __init__(self, explicit_ordinal=None):
     self.explicit_ordinal = explicit_ordinal
     self.ordinal = explicit_ordinal
diff --git a/utils/ipc/mojo/public/tools/bindings/mojom_types_downgrader.py b/utils/ipc/mojo/public/tools/bindings/mojom_types_downgrader.py
deleted file mode 100755
index 15f0e3ba..00000000
--- a/utils/ipc/mojo/public/tools/bindings/mojom_types_downgrader.py
+++ /dev/null
@@ -1,119 +0,0 @@
-#!/usr/bin/env python
-# Copyright 2020 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-"""Downgrades *.mojom files to the old mojo types for remotes and receivers."""
-
-import argparse
-import fnmatch
-import os
-import re
-import shutil
-import sys
-import tempfile
-
-# List of patterns and replacements to match and use against the contents of a
-# mojo file. Each replacement string will be used with Python string's format()
-# function, so the '{}' substring is used to mark where the mojo type should go.
-_MOJO_REPLACEMENTS = {
-    r'pending_remote': r'{}',
-    r'pending_receiver': r'{}&',
-    r'pending_associated_remote': r'associated {}',
-    r'pending_associated_receiver': r'associated {}&',
-}
-
-# Pre-compiled regular expression that matches against any of the replacements.
-_REGEXP_PATTERN = re.compile(
-    r'|'.join(
-        ['{}\s*<\s*(.*?)\s*>'.format(k) for k in _MOJO_REPLACEMENTS.keys()]),
-    flags=re.DOTALL)
-
-
-def ReplaceFunction(match_object):
-  """Returns the right replacement for the string matched against the regexp."""
-  for index, (match, repl) in enumerate(_MOJO_REPLACEMENTS.items(), 1):
-    if match_object.group(0).startswith(match):
-      return repl.format(match_object.group(index))
-
-
-def DowngradeFile(path, output_dir=None):
-  """Downgrades the mojom file specified by |path| to the old mojo types.
-
-  Optionally pass |output_dir| to place the result under a separate output
-  directory, preserving the relative path to the file included in |path|.
-  """
-  # Use a temporary file to dump the new contents after replacing the patterns.
-  with open(path) as src_mojo_file:
-    with tempfile.NamedTemporaryFile(mode='w', delete=False) as tmp_mojo_file:
-      tmp_contents = _REGEXP_PATTERN.sub(ReplaceFunction, src_mojo_file.read())
-      tmp_mojo_file.write(tmp_contents)
-
-  # Files should be placed in the desired output directory
-  if output_dir:
-    output_filepath = os.path.join(output_dir, os.path.basename(path))
-    if not os.path.exists(output_dir):
-      os.makedirs(output_dir)
-  else:
-    output_filepath = path
-
-  # Write the new contents preserving the original file's attributes.
-  shutil.copystat(path, tmp_mojo_file.name)
-  shutil.move(tmp_mojo_file.name, output_filepath)
-
-  # Make sure to "touch" the new file so that access, modify and change times
-  # are always newer than the source file's, otherwise Modify time will be kept
-  # as per the call to shutil.copystat(), causing unnecessary generations of the
-  # output file in subsequent builds due to ninja considering it dirty.
-  os.utime(output_filepath, None)
-
-
-def DowngradeDirectory(path, output_dir=None):
-  """Downgrades mojom files inside directory |path| to the old mojo types.
-
-  Optionally pass |output_dir| to place the result under a separate output
-  directory, preserving the relative path to the file included in |path|.
-  """
-  # We don't have recursive glob.glob() nor pathlib.Path.rglob() in Python 2.7
-  mojom_filepaths = []
-  for dir_path, _, filenames in os.walk(path):
-    for filename in fnmatch.filter(filenames, "*mojom"):
-      mojom_filepaths.append(os.path.join(dir_path, filename))
-
-  for path in mojom_filepaths:
-    absolute_dirpath = os.path.dirname(os.path.abspath(path))
-    if output_dir:
-      dest_dirpath = output_dir + absolute_dirpath
-    else:
-      dest_dirpath = absolute_dirpath
-    DowngradeFile(path, dest_dirpath)
-
-
-def DowngradePath(src_path, output_dir=None):
-  """Downgrades the mojom files pointed by |src_path| to the old mojo types.
-
-  Optionally pass |output_dir| to place the result under a separate output
-  directory, preserving the relative path to the file included in |path|.
-  """
-  if os.path.isdir(src_path):
-    DowngradeDirectory(src_path, output_dir)
-  elif os.path.isfile(src_path):
-    DowngradeFile(src_path, output_dir)
-  else:
-    print(">>> {} not pointing to a valid file or directory".format(src_path))
-    sys.exit(1)
-
-
-def main():
-  parser = argparse.ArgumentParser(
-      description="Downgrade *.mojom files to use the old mojo types.")
-  parser.add_argument(
-      "srcpath", help="path to the file or directory to apply the conversion")
-  parser.add_argument(
-      "--outdir", help="the directory to place the converted file(s) under")
-  args = parser.parse_args()
-
-  DowngradePath(args.srcpath, args.outdir)
-
-
-if __name__ == "__main__":
-  sys.exit(main())
diff --git a/utils/ipc/mojo/public/tools/bindings/validate_typemap_config.py b/utils/ipc/mojo/public/tools/bindings/validate_typemap_config.py
index f1783d59..6bb7a209 100755
--- a/utils/ipc/mojo/public/tools/bindings/validate_typemap_config.py
+++ b/utils/ipc/mojo/public/tools/bindings/validate_typemap_config.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright 2020 The Chromium Authors. All rights reserved.
+# 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.
 
@@ -17,7 +17,8 @@ def CheckCppTypemapConfigs(target_name, config_filename, out_filename):
   ])
   _SUPPORTED_TYPE_KEYS = set([
       'mojom', 'cpp', 'copyable_pass_by_value', 'force_serialize', 'hashable',
-      'move_only', 'nullable_is_same_type'
+      'move_only', 'nullable_is_same_type', 'forward_declaration',
+      'default_constructible'
   ])
   with open(config_filename, 'r') as f:
     for config in json.load(f):