Add Observer in FaviconTabHelper

chrome/chrome_browser.gypi

 # Copyright 2012 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': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
@@ skipping 380 matching lines @@
       'browser/favicon/chrome_favicon_client_factory.cc',
       'browser/favicon/chrome_favicon_client_factory.h',
       'browser/favicon/favicon_handler.cc',
       'browser/favicon/favicon_handler.h',
       'browser/favicon/favicon_service.cc',
       'browser/favicon/favicon_service.h',
       'browser/favicon/favicon_service_factory.cc',
       'browser/favicon/favicon_service_factory.h',
       'browser/favicon/favicon_tab_helper.cc',
       'browser/favicon/favicon_tab_helper.h',
+      'browser/favicon/favicon_tab_helper_observer.cc',
+      'browser/favicon/favicon_tab_helper_observer.h',
       'browser/file_select_helper.cc',
       'browser/file_select_helper.h',
       'browser/file_select_helper_mac.mm',
       'browser/flags_storage.h',
       'browser/fullscreen.h',
       'browser/fullscreen_chromeos.cc',
       'browser/fullscreen_mac.mm',
       'browser/fullscreen_win.cc',
       'browser/geolocation/chrome_access_token_store.cc',
       'browser/geolocation/chrome_access_token_store.h',
@@ skipping 3186 matching lines @@
           'variables': {
             'proto_in_dir': 'browser/sync_file_system/drive_backend',
             'proto_out_dir': 'chrome/browser/sync_file_system/drive_backend',
           },
           'includes': [ '../build/protoc.gypi' ]
         },
       ],
     },],
   ],
 }