chrome: Cleanup class/struct forward declarations

chrome/browser/ui/views/message_center/web_notification_tray.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_WEB_NOTIFICATION_TRAY_H_
 #define CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_WEB_NOTIFICATION_TRAY_H_
 
 #include <memory>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "ui/message_center/message_center_tray_delegate.h"
 #include "ui/views/widget/widget_observer.h"
 
-class StatusIcon;
-
 namespace message_center {
 class DesktopPopupAlignmentDelegate;
 class MessageCenter;
 class MessageCenterTray;
 class MessagePopupCollection;
 
 // A MessageCenterTrayDelegate implementation that exposes the MessageCenterTray
 // via a system tray icon.  The notification popups will be displayed in the
 // corner of the screen and the message center will be displayed by the system
 // tray icon on click.
@@ skipping 24 matching lines @@
   std::unique_ptr<MessagePopupCollection> popup_collection_;
   std::unique_ptr<DesktopPopupAlignmentDelegate> alignment_delegate_;
 
   std::unique_ptr<MessageCenterTray> message_center_tray_;
   DISALLOW_COPY_AND_ASSIGN(WebNotificationTray);
 };
 
 }  // namespace message_center
 
 #endif  // CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_WEB_NOTIFICATION_TRAY_H_