Enable use_once_callback on mojom GN rule by default

third_party/WebKit/public/BUILD.gn

 # Copyright 2014 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("//build/buildflag_header.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/config.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 import("//tools/grit/grit_rule.gni")
@@ skipping 729 matching lines @@
   # inside content.
   export_class_attribute = "CONTENT_EXPORT"
   export_define = "CONTENT_IMPLEMENTATION=1"
   export_header = "content/common/content_export.h"
 
   # Similarly, the blink variant must be linked with the platform component
   # since it uses types from it in its typemaps.
   export_class_attribute_blink = "BLINK_PLATFORM_EXPORT"
   export_define_blink = "BLINK_PLATFORM_IMPLEMENTATION=1"
   export_header_blink = "third_party/WebKit/public/platform/WebCommon.h"
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 mojom("android_mojo_bindings") {
   visibility = [ ":mojo_bindings" ]
   visibility_blink = [ ":mojo_bindings_blink" ]
   sources = [
     "platform/modules/document_metadata/copyless_paste.mojom",
     "platform/modules/installation/installation.mojom",
     "platform/modules/installedapp/installed_app_provider.mojom",
     "platform/modules/installedapp/related_application.mojom",
     "platform/modules/webshare/webshare.mojom",
   ]
   public_deps = [
     "//components/payments/mojom",
     "//url/mojo:url_mojom_gurl",
   ]
 
   # See comment above.
   export_class_attribute = "CONTENT_EXPORT"
   export_define = "CONTENT_IMPLEMENTATION=1"
   export_header = "content/common/content_export.h"
   export_class_attribute_blink = "BLINK_PLATFORM_EXPORT"
   export_define_blink = "BLINK_PLATFORM_IMPLEMENTATION=1"
   export_header_blink = "third_party/WebKit/public/platform/WebCommon.h"
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 # The offscreen_canvas_mojo_bindings is separated from the rest of mojom files
 # because its deps contain too many files in Chromium that would pollute the
 # include paths in generated mojom-blink files for other services.
 mojom("offscreen_canvas_mojo_bindings") {
   visibility = [ "//content/*" ]
   visibility_blink = [ "//third_party/WebKit/Source/platform" ]
   sources = [
     "platform/modules/offscreencanvas/offscreen_canvas_surface.mojom",
   ]
   deps = [
     "//cc/ipc:interfaces",
   ]
 
   # See comment above
   export_class_attribute = "CONTENT_EXPORT"
   export_define = "CONTENT_IMPLEMENTATION=1"
   export_header = "content/common/content_export.h"
   export_class_attribute_blink = "BLINK_PLATFORM_EXPORT"
   export_define_blink = "BLINK_PLATFORM_IMPLEMENTATION=1"
   export_header_blink = "third_party/WebKit/public/platform/WebCommon.h"
-  use_once_callback = true
 }
 
 group("generate_mojo_bindings") {
   deps = [
     ":mojo_bindings_blink__generator",
     ":offscreen_canvas_mojo_bindings_blink__generator",
   ]
 }
 
 # Some mojom typemaps are shared between Chromium and Blink variants and
 # therefore require some shared traits implementation. These definitions are
 # relegated to a separate target to avoid duplication between the variants.
 source_set("shared_typemap_traits") {
   visibility = [ ":*" ]
   sources = [
     "web/ConsoleMessageStructTraits.cpp",
     "web/ConsoleMessageStructTraits.h",
   ]
   deps = [
     ":blink_headers",
     ":mojo_bindings_shared__generator",
     "//mojo/public/cpp/bindings:struct_traits",
   ]
 }