Add extensions code to use common updater in components/update_client/

extensions/extensions.gypi

 # 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.
 
 {
   'variables': {
     'extensions_common_constants_sources': [
       'common/constants.cc',
       'common/constants.h',
     ],
@@ skipping 734 matching lines @@
       'browser/updater/extension_downloader_delegate.cc',
       'browser/updater/extension_downloader_delegate.h',
       'browser/updater/manifest_fetch_data.cc',
       'browser/updater/manifest_fetch_data.h',
       'browser/updater/null_extension_cache.cc',
       'browser/updater/null_extension_cache.h',
       'browser/updater/request_queue.h',
       'browser/updater/request_queue_impl.h',
       'browser/updater/safe_manifest_parser.cc',
       'browser/updater/safe_manifest_parser.h',
+      'browser/updater/update_client_config.cc',
+      'browser/updater/update_client_config.h',
+      'browser/updater/update_data_provider.cc',
+      'browser/updater/update_data_provider.h',
+      'browser/updater/update_install_shim.cc',
+      'browser/updater/update_install_shim.h',
       'browser/updater/update_service.cc',
       'browser/updater/update_service.h',
       'browser/updater/update_service_factory.cc',
       'browser/updater/update_service_factory.h',
       'browser/url_request_util.cc',
       'browser/url_request_util.h',
       'browser/user_script_loader.cc',
       'browser/user_script_loader.h',
       'browser/value_store/leveldb_value_store.cc',
       'browser/value_store/leveldb_value_store.h',
@@ skipping 289 matching lines @@
       'test/result_catcher.h',
       'test/test_content_utility_client.cc',
       'test/test_content_utility_client.h',
       'test/test_extensions_client.cc',
       'test/test_extensions_client.h',
       'test/test_permission_message_provider.cc',
       'test/test_permission_message_provider.h',
     ],
   },
 }