Remove the notificationProvider extension API

chrome/browser/extensions/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/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//rlz/features/features.gni")
@@ skipping 295 matching lines @@
     "api/music_manager_private/device_id_win.cc",
     "api/music_manager_private/music_manager_private_api.cc",
     "api/music_manager_private/music_manager_private_api.h",
     "api/networking_private/networking_private_credentials_getter_chromeos.cc",
     "api/networking_private/networking_private_ui_delegate_chromeos.cc",
     "api/networking_private/networking_private_ui_delegate_chromeos.h",
     "api/networking_private/networking_private_ui_delegate_factory_impl.cc",
     "api/networking_private/networking_private_ui_delegate_factory_impl.h",
     "api/networking_private/networking_private_verify_delegate_factory_impl.cc",
     "api/networking_private/networking_private_verify_delegate_factory_impl.h",
-    "api/notification_provider/notification_provider_api.cc",
-    "api/notification_provider/notification_provider_api.h",
     "api/notifications/notifications_api.cc",
     "api/notifications/notifications_api.h",
     "api/omnibox/omnibox_api.cc",
     "api/omnibox/omnibox_api.h",
     "api/page_capture/page_capture_api.cc",
     "api/page_capture/page_capture_api.h",
     "api/passwords_private/passwords_private_api.cc",
     "api/passwords_private/passwords_private_api.h",
     "api/passwords_private/passwords_private_delegate.h",
     "api/passwords_private/passwords_private_delegate_factory.cc",
@@ skipping 856 matching lines @@
       "api/braille_display_private/brlapi_connection.cc",
       "api/braille_display_private/brlapi_connection.h",
       "api/braille_display_private/brlapi_keycode_map.cc",
       "api/braille_display_private/brlapi_keycode_map.h",
     ]
     deps += [ "//build/linux/libbrlapi" ]
   } else {
     sources += [ "api/braille_display_private/braille_controller_stub.cc" ]
   }
 }