Modify languageSettingsPrivate IDL and flesh out stub implementation

chrome/chrome_browser_extensions.gypi

 # Copyright (c) 2013 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': {
     'chrome_browser_extensions_chromeos_sources': [
       'browser/extensions/api/enterprise_device_attributes/enterprise_device_attributes_api.cc',
       'browser/extensions/api/enterprise_device_attributes/enterprise_device_attributes_api.h',
       'browser/extensions/api/enterprise_platform_keys/enterprise_platform_keys_api.cc',
@@ skipping 311 matching lines @@
       'browser/extensions/api/image_writer_private/write_from_file_operation.cc',
       'browser/extensions/api/image_writer_private/write_from_file_operation.h',
       'browser/extensions/api/image_writer_private/write_from_url_operation.cc',
       'browser/extensions/api/image_writer_private/write_from_url_operation.h',
       'browser/extensions/api/inline_install_private/inline_install_private_api.cc',
       'browser/extensions/api/inline_install_private/inline_install_private_api.h',
       'browser/extensions/api/instance_id/instance_id_api.cc',
       'browser/extensions/api/instance_id/instance_id_api.h',
       'browser/extensions/api/language_settings_private/language_settings_private_api.cc',
       'browser/extensions/api/language_settings_private/language_settings_private_api.h',
+      'browser/extensions/api/language_settings_private/language_settings_private_delegate.cc',
+      'browser/extensions/api/language_settings_private/language_settings_private_delegate.h',
+      'browser/extensions/api/language_settings_private/language_settings_private_delegate_factory.cc',
+      'browser/extensions/api/language_settings_private/language_settings_private_delegate_factory.h',
       'browser/extensions/api/launcher_page/launcher_page_api.cc',
       'browser/extensions/api/launcher_page/launcher_page_api.h',
       'browser/extensions/api/location/location_api.cc',
       'browser/extensions/api/location/location_api.h',
       'browser/extensions/api/location/location_manager.cc',
       'browser/extensions/api/location/location_manager.h',
       'browser/extensions/api/management/chrome_management_api_delegate.cc',
       'browser/extensions/api/management/chrome_management_api_delegate.h',
       'browser/extensions/api/mdns/dns_sd_delegate.cc',
       'browser/extensions/api/mdns/dns_sd_delegate.h',
@@ skipping 783 matching lines @@
           ],
         }, {  # use_brlapi==0
           'sources': [
             'browser/extensions/api/braille_display_private/braille_controller_stub.cc',
           ],
         }],
       ],
     },
   ],
 }