Remove the notificationProvider extension API

chrome/browser/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 3259 matching lines @@
       "notifications/fullscreen_notification_blocker.cc",
       "notifications/fullscreen_notification_blocker.h",
       "notifications/google_now_notification_stats_collector.cc",
       "notifications/google_now_notification_stats_collector.h",
       "notifications/message_center_notification_manager.cc",
       "notifications/message_center_notification_manager.h",
       "notifications/message_center_settings_controller.cc",
       "notifications/message_center_settings_controller.h",
       "notifications/message_center_stats_collector.cc",
       "notifications/message_center_stats_collector.h",
-      "notifications/notification_conversion_helper.cc",
-      "notifications/notification_conversion_helper.h",
       "notifications/notification_system_observer.cc",
       "notifications/notification_system_observer.h",
       "notifications/notification_ui_manager_desktop.cc",
       "notifications/notifier_source.h",
       "notifications/profile_notification.cc",
       "notifications/profile_notification.h",
       "notifications/screen_lock_notification_blocker.cc",
       "notifications/screen_lock_notification_blocker.h",
       "notifications/system_component_notifier_source_chromeos.cc",
       "notifications/system_component_notifier_source_chromeos.h",
@@ skipping 1210 matching lines @@
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }
 
 service_manifest("preferences_manifest") {
   name = "preferences"
   source = "prefs/preferences_manifest.json"
 }