Make the hcsm and its providers communicate via an observer interface.

chrome/chrome_browser.gypi

 # Copyright (c) 2011 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',
       'type': 'static_library',
       'dependencies': [
@@ skipping 731 matching lines @@
         'browser/chromeos/web_socket_proxy.cc',
         'browser/chromeos/web_socket_proxy.h',
         'browser/chromeos/wm_ipc.cc',
         'browser/chromeos/wm_ipc.h',
         'browser/chromeos/wm_message_listener.cc',
         'browser/chromeos/wm_message_listener.h',
         'browser/chromeos/xinput_hierarchy_changed_event_listener.cc',
         'browser/chromeos/xinput_hierarchy_changed_event_listener.h',
         'browser/command_updater.cc',
         'browser/command_updater.h',
+        'browser/content_settings/content_settings_abstract_provider.cc',
+        'browser/content_settings/content_settings_abstract_provider.h',
         'browser/content_settings/content_settings_details.cc',
         'browser/content_settings/content_settings_details.h',
         'browser/content_settings/content_settings_extension_provider.cc',
         'browser/content_settings/content_settings_extension_provider.h',
         'browser/content_settings/content_settings_notification_provider.cc',
         'browser/content_settings/content_settings_notification_provider.h',
+        'browser/content_settings/content_settings_observer.h',
         'browser/content_settings/content_settings_origin_identifier_value_map.cc',
         'browser/content_settings/content_settings_origin_identifier_value_map.h',
         'browser/content_settings/content_settings_pattern.cc',
         'browser/content_settings/content_settings_pattern.h',
         'browser/content_settings/content_settings_pattern_parser.cc',
         'browser/content_settings/content_settings_pattern_parser.h',
         'browser/content_settings/content_settings_policy_provider.cc',
         'browser/content_settings/content_settings_policy_provider.h',
         'browser/content_settings/content_settings_pref_provider.cc',
         'browser/content_settings/content_settings_pref_provider.h',
@@ skipping 4023 matching lines @@
       ],
       'export_dependent_settings': [
         'in_memory_url_index_cache_proto',
       ],
       # This target exports a hard dependency because it includes generated
       # header files.
       'hard_dependency': 1,
     },
   ],
 }