Abstract notification clicks in its own dictionary

chrome/browser/ui/cocoa/notifications/notification_common.gyp

 # Copyright 2016 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.
 
 {
 'targets': [
   {
     # GN version: //chrome/browser/ui/notifications:common
     'target_name': 'notification_common',
     'type': 'static_library',
       'include_dirs': [
         '<(DEPTH)',
       ],
     'sources': [
       'notification_builder_mac.h',
       'notification_builder_mac.mm',
+      'notification_constants_mac.h',
+      'notification_constants_mac.mm',
+      'notification_response_builder_mac.h',
+      'notification_response_builder_mac.mm',
     ],
     'dependencies': [
       '<(DEPTH)/base/base.gyp:base',
       '<(DEPTH)/chrome/chrome_resources.gyp:chrome_strings',
       '<(DEPTH)/ui/base/ui_base.gyp:ui_base',
     ],
   },
 ],
 }