ash: Cleanup class/struct forward declarations

ash/common/system/web_notification/web_notification_tray.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 ASH_COMMON_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_
 #define ASH_COMMON_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 #include "ash/common/system/tray/tray_background_view.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "ui/base/models/simple_menu_model.h"
 #include "ui/gfx/animation/animation_container.h"
 #include "ui/message_center/message_center_tray.h"
 #include "ui/message_center/message_center_tray_delegate.h"
 #include "ui/views/bubble/tray_bubble_view.h"
 
 // Status area tray for showing browser and app notifications. This hosts
 // a MessageCenter class which manages the notification list. This class
 // contains the Ash specific tray implementation.
 //
 // Note: These are not related to system notifications (i.e NotificationView
 // generated by SystemTrayItem). Visibility of one notification type or other
 // is controlled by StatusAreaWidget.
 
-namespace views {
-class MenuRunner;
-}
-
 namespace message_center {
-class MessageBubbleBase;
 class MessageCenter;
 class MessageCenterBubble;
 class MessagePopupCollection;
 }
 
 namespace ash {
 class AshPopupAlignmentDelegate;
 class SystemTray;
 class WebNotificationBubbleWrapper;
-class WebNotificationButton;
 class WebNotificationImage;
 class WebNotificationLabel;
 class WmWindow;
 
 class ASH_EXPORT WebNotificationTray
     : public TrayBackgroundView,
       public views::TrayBubbleView::Delegate,
       public message_center::MessageCenterTrayDelegate,
       public base::SupportsWeakPtr<WebNotificationTray>,
       public ui::SimpleMenuModel::Delegate {
@@ skipping 134 matching lines @@
   bool should_block_shelf_auto_hide_;
 
   std::unique_ptr<AshPopupAlignmentDelegate> popup_alignment_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(WebNotificationTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_