[Favicon] Adding chrome://fallback-icon host for Fallback Icon "Explicit Flow"

chrome/chrome_browser_ui.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': {
     # There are two sections of sources:
     # * "Platform"-based sources (OS, toolkit, etc.)
     # * Feature/directory-based sources (e.g., history, printing)
 
@@ skipping 1016 matching lines @@
       'browser/ui/webui/constrained_web_dialog_ui.cc',
       'browser/ui/webui/constrained_web_dialog_ui.h',
       'browser/ui/webui/cookies_tree_model_util.cc',
       'browser/ui/webui/cookies_tree_model_util.h',
       'browser/ui/webui/crashes_ui.cc',
       'browser/ui/webui/crashes_ui.h',
       'browser/ui/webui/device_log_ui.cc',
       'browser/ui/webui/device_log_ui.h',
       'browser/ui/webui/domain_reliability_internals_ui.cc',
       'browser/ui/webui/domain_reliability_internals_ui.h',
+      'browser/ui/webui/fallback_icon_source.cc',
+      'browser/ui/webui/fallback_icon_source.h',
       'browser/ui/webui/favicon_source.cc',
       'browser/ui/webui/favicon_source.h',
       'browser/ui/webui/fileicon_source.cc',
       'browser/ui/webui/fileicon_source.h',
       'browser/ui/webui/flags_ui.cc',
       'browser/ui/webui/flags_ui.h',
       'browser/ui/webui/gcm_internals_ui.cc',
       'browser/ui/webui/gcm_internals_ui.h',
       'browser/ui/webui/history_ui.cc',
       'browser/ui/webui/history_ui.h',
@@ skipping 2101 matching lines @@
           ],
           'sources': [
             '<@(chrome_browser_ui_non_mobile_sources)',
             '<@(chrome_browser_ui_omnibox_non_mobile_sources)',
           ],
         }],
       ],
     },
   ],
 }