Implement support for fallback update check urls in the component updater

components/component_updater.gypi

 # 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.
 
 {
   'targets': [
     {
       # GN version: //components/component_updater
       'target_name': 'component_updater',
       'type': 'static_library',
@@ skipping 31 matching lines @@
         'component_updater/component_updater_switches.h',
         'component_updater/component_updater_utils.cc',
         'component_updater/component_updater_utils.h',
         'component_updater/crx_update_item.h',
         'component_updater/crx_downloader.cc',
         'component_updater/crx_downloader.h',
         'component_updater/default_component_installer.cc',
         'component_updater/default_component_installer.h',
         'component_updater/pref_names.cc',
         'component_updater/pref_names.h',
+        'component_updater/request_sender.cc',
+        'component_updater/request_sender.h',
         'component_updater/update_checker.cc',
         'component_updater/update_checker.h',
         'component_updater/update_response.cc',
         'component_updater/update_response.h',
         'component_updater/url_fetcher_downloader.cc',
         'component_updater/url_fetcher_downloader.h',
       ],
     },
     {
       # GN version: //components/component_updater:test_support
       'target_name': 'component_updater_test_support',
       'type': 'static_library',
       'dependencies': [
         'component_updater',
         '../testing/gmock.gyp:gmock',
         '../testing/gtest.gyp:gtest',
       ],
       'sources': [
         'component_updater/test/test_configurator.cc',
         'component_updater/test/test_configurator.h',
         'component_updater/test/test_installer.cc',
         'component_updater/test/test_installer.h',
         'component_updater/test/url_request_post_interceptor.cc',
         'component_updater/test/url_request_post_interceptor.h',
       ],
     },
   ],
 }