ui: Cleanup class/struct forward declarations

ui/message_center/notification_list.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_MESSAGE_CENTER_NOTIFICATION_LIST_H_
 #define UI_MESSAGE_CENTER_NOTIFICATION_LIST_H_
 
 #include <stddef.h>
 
 #include <list>
 #include <set>
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/notification_blocker.h"
 #include "ui/message_center/notification_types.h"
 
 namespace base {
-class DictionaryValue;
 class TimeDelta;
 }
 
 namespace gfx {
 class Image;
 }
 
 namespace message_center {
 
 namespace test {
@@ skipping 131 matching lines @@
   MessageCenter* message_center_;  // owner
   OwnedNotifications notifications_;
   bool quiet_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationList);
 };
 
 }  // namespace message_center
 
 #endif // UI_MESSAGE_CENTER_NOTIFICATION_LIST_H_