Extract RuntimeEventRouter from extensions Runtime API

chrome/chrome_browser_extensions.gypi

 # Copyright (c) 2013 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.
 
 {
   'targets': [
     {
       'target_name': 'browser_extensions',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 951 matching lines @@
             ['include', '^browser/extensions/api/messaging/extension_message_port.cc'],
             ['include', '^browser/extensions/api/messaging/incognito_connectability.cc'],
             ['include', '^browser/extensions/api/messaging/message_property_provider.cc'],
             ['include', '^browser/extensions/api/messaging/message_service.cc'],
             ['include', '^browser/extensions/api/module/module.cc'],
             ['include', '^browser/extensions/api/networking_private/.*\.cc'],
             ['include', '^browser/extensions/api/omnibox/omnibox_api.cc'],
             ['include', '^browser/extensions/api/preference/preference_api.cc'],
             ['include', '^browser/extensions/api/proxy/proxy_api.cc'],
             ['include', '^browser/extensions/api/proxy/proxy_api_constants.cc'],
-            ['include', '^browser/extensions/api/runtime/runtime_api.cc'],
             ['include', '^browser/extensions/api/tabs/tabs_constants.cc'],
             ['include', '^browser/extensions/api/web_navigation/frame_navigation_state.cc'],
             ['include', '^browser/extensions/api/web_navigation/web_navigation_api.cc'],
             ['include', '^browser/extensions/api/web_navigation/web_navigation_api_constants.cc'],
             ['include', '^browser/extensions/api/web_navigation/web_navigation_api_helpers.cc'],
             ['include', '^browser/extensions/api/web_request/form_data_parser.cc'],
             ['include', '^browser/extensions/api/web_request/upload_data_presenter.cc'],
             ['include', '^browser/extensions/api/web_request/web_request_api.cc'],
             ['include', '^browser/extensions/api/web_request/web_request_api_constants.cc'],
             ['include', '^browser/extensions/api/web_request/web_request_api_helpers.cc'],
@@ skipping 198 matching lines @@
       'type': 'static_library',
       'sources': [ 'browser/extensions/api/cast_channel/cast_channel.proto' ],
       'variables': {
           'proto_in_dir': 'browser/extensions/api/cast_channel',
           'proto_out_dir': 'chrome/browser/extensions/api/cast_channel',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],  # 'conditions'
 }