Move enable_webrtc to a buildflag header.

chrome/common/extensions/api/BUILD.gn

 # Copyright 2015 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/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 import("//extensions/features/features.gni")
+import("//media/media_options.gni")
 import("//tools/json_schema_compiler/json_features.gni")
 import("//tools/json_schema_compiler/json_schema_api.gni")
 
 assert(enable_extensions)
 
 schema_sources = [
   "accessibility_features.json",
   "accessibility_private.json",
   "activity_log_private.json",
   "autofill_private.idl",
@@ skipping 51 matching lines @@
   "signed_in_devices.idl",
   "streams_private.idl",
   "sync_file_system.idl",
   "system_indicator.idl",
   "system_private.json",
   "tab_capture.idl",
   "tabs.json",
   "types.json",
   "web_navigation.json",
 
-  # Despite the name, this API does not rely on any
-  # WebRTC-specific bits and as such does not belong in
-  # the enable_webrtc==0 section below.
+  # Despite the name, these APIs do not rely on any WebRTC-specific bits and as
+  # such do not belong in a conditional.
   "webrtc_audio_private.idl",
   "webrtc_desktop_capture_private.idl",
   "webrtc_logging_private.idl",
   "webstore_private.json",
   "webstore_widget_private.idl",
   "windows.json",
 ]
 if (enable_task_manager) {
   schema_sources += [ "processes.idl" ]
 }
@@ skipping 174 matching lines @@
 }
 
 group("extensions_features") {
   public_deps = [
     ":api_features",
     ":behavior_features",
     ":manifest_features",
     ":permission_features",
   ]
 }