Implement message center on Windows

ui/message_center/message_center.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_MESSAGE_CENTER_H_
 #define UI_MESSAGE_CENTER_MESSAGE_CENTER_H_
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/notification_list.h"
 #include "ui/notifications/notification_types.h"
 
-template <typename T> struct DefaultSingletonTraits;
-
 namespace base {
 class DictionaryValue;
 }
 
 // Class for managing the NotificationList. The client (e.g. Chrome) calls
 // [Add|Remove|Update]Notification to create and update notifications in the
 // list. It can also implement Delegate to receive callbacks when a
 // notification is removed (closed), or clicked on.
 // If an Observer is provided, it will be informed when the notification list
 // changes, and is expected to handle creating, showing, and hiding of any
@@ skipping 130 matching lines @@
   scoped_ptr<NotificationList> notification_list_;
   ObserverList<Observer> observer_list_;
   Delegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageCenter);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_MESSAGE_CENTER_H_