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:notification_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',
         ],
     }
   ]
 }