Delete deprecated synced notifications code

chrome/chrome_tests_unit.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': {
     'chrome_unit_tests_sources': [
       '../apps/saved_files_service_unittest.cc',
       '../components/autofill/content/renderer/test_password_autofill_agent.cc',
       '../components/autofill/content/renderer/test_password_autofill_agent.h',
       '../components/autofill/content/renderer/test_password_generation_agent.cc',
@@ skipping 345 matching lines @@
       'browser/extensions/api/signed_in_devices/signed_in_devices_manager_unittest.cc',
       'browser/extensions/api/socket/socket_api_unittest.cc',
       'browser/extensions/api/socket/tcp_socket_unittest.cc',
       'browser/extensions/api/socket/tls_socket_unittest.cc',
       'browser/extensions/api/socket/udp_socket_unittest.cc',
       'browser/extensions/api/sockets_tcp_server/sockets_tcp_server_api_unittest.cc',
       'browser/extensions/api/sockets_udp/sockets_udp_api_unittest.cc',
       'browser/extensions/api/storage/policy_value_store_unittest.cc',
       'browser/extensions/api/storage/settings_sync_unittest.cc',
       'browser/extensions/api/streams_private/streams_private_manifest_unittest.cc',
-      'browser/extensions/api/synced_notifications_private/synced_notifications_shim_unittest.cc',
       'browser/extensions/api/web_navigation/frame_navigation_state_unittest.cc',
       'browser/extensions/api/web_request/web_request_api_unittest.cc',
       'browser/extensions/api/web_request/web_request_permissions_unittest.cc',
       'browser/extensions/app_sync_data_unittest.cc',
       'browser/extensions/blacklist_state_fetcher_unittest.cc',
       'browser/extensions/bookmark_app_helper_unittest.cc',
       'browser/extensions/browser_permissions_policy_delegate_unittest.cc',
       'browser/extensions/chrome_app_sorting_unittest.cc',
       'browser/extensions/chrome_component_extension_resource_manager_unittest.cc',
       'browser/extensions/chrome_info_map_unittest.cc',
@@ skipping 2565 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }