Do not delete notification ids unknown by the display service

content/test/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ skipping 149 matching lines @@
     "mock_google_streaming_server.cc",
     "mock_google_streaming_server.h",
     "mock_keyboard.cc",
     "mock_keyboard.h",
     "mock_keyboard_driver_win.cc",
     "mock_keyboard_driver_win.h",
     "mock_leveldb_database.cc",
     "mock_leveldb_database.h",
     "mock_permission_manager.cc",
     "mock_permission_manager.h",
-    "mock_platform_notification_service.cc",
-    "mock_platform_notification_service.h",
     "mock_render_process.cc",
     "mock_render_process.h",
     "mock_ssl_host_state_delegate.cc",
     "mock_ssl_host_state_delegate.h",
     "mock_webassociatedurlloader.cc",
     "mock_webassociatedurlloader.h",
     "mock_webblob_registry_impl.cc",
     "mock_webblob_registry_impl.h",
     "mock_webclipboard_impl.cc",
     "mock_webclipboard_impl.h",
@@ skipping 1645 matching lines @@
   if (is_android) {
     deps += [ "//testing/android/native_test:native_test_native_code" ]
   }
 }
 
 group("fuzzers") {
   deps = [
     "//content/test/fuzzer",
   ]
 }