Factor out a PendingNotificationTracker from the NotificationManager.

content/content_child.gypi

 # Copyright 2013 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../components/tracing.gyp:tracing',
     '../mojo/mojo_base.gyp:mojo_environment_chromium',
     '../mojo/mojo_base.gyp:mojo_common_lib',
@@ skipping 101 matching lines @@
       'child/navigator_connect/navigator_connect_provider.cc',
       'child/navigator_connect/navigator_connect_provider.h',
       'child/notifications/notification_data_conversions.cc',
       'child/notifications/notification_data_conversions.h',
       'child/notifications/notification_dispatcher.cc',
       'child/notifications/notification_dispatcher.h',
       'child/notifications/notification_image_loader.cc',
       'child/notifications/notification_image_loader.h',
       'child/notifications/notification_manager.cc',
       'child/notifications/notification_manager.h',
+      'child/notifications/pending_notifications_tracker.cc',
+      'child/notifications/pending_notifications_tracker.h',
       'child/npapi/np_channel_base.cc',
       'child/npapi/np_channel_base.h',
       'child/npapi/npobject_base.h',
       'child/npapi/npobject_proxy.cc',
       'child/npapi/npobject_proxy.h',
       'child/npapi/npobject_stub.cc',
       'child/npapi/npobject_stub.h',
       'child/npapi/npobject_util.cc',
       'child/npapi/npobject_util.h',
       'child/npapi/npruntime_util.cc',
@@ skipping 266 matching lines @@
         }, {
           'dependencies': [
             '../third_party/nss/nss.gyp:nspr',
             '../third_party/nss/nss.gyp:nss',
           ],
         }],
       ],
     }],
   ],
 }