Reland: mash: Convert TrayBackgroundView to wm common types

ash/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_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_
 #define ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
-#include "ash/system/tray/tray_background_view.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/message_center/message_center_tray.h"
 #include "ui/message_center/message_center_tray_delegate.h"
 #include "ui/views/bubble/tray_bubble_view.h"
 #include "ui/views/controls/button/button.h"
 
 // Status area tray for showing browser and app notifications. This hosts
@@ skipping 139 matching lines @@
   }
 
   // Returns true if any user is logged in and the system is not at the screen
   // for adding a secondary user.
   bool IsLoggedIn() const;
 
   // Testing accessors.
   bool IsPopupVisible() const;
   message_center::MessageCenterBubble* GetMessageCenterBubbleForTest();
 
+  StatusAreaWidget* status_area_widget_;
   std::unique_ptr<message_center::MessageCenterTray> message_center_tray_;
   std::unique_ptr<WebNotificationBubbleWrapper> message_center_bubble_;
   std::unique_ptr<message_center::MessagePopupCollection> popup_collection_;
   WebNotificationButton* button_;
 
   bool show_message_center_on_unlock_;
 
   bool should_update_tray_content_;
 
   // True when the shelf auto hide behavior has to be blocked. Previously
   // this was done by checking |message_center_bubble_| but actually
   // the check can be called when creating this object, so it would cause
   // flickers of the shelf from hidden to shown. See: crbug.com/181213
   bool should_block_shelf_auto_hide_;
 
   std::unique_ptr<AshPopupAlignmentDelegate> popup_alignment_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(WebNotificationTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_WEB_NOTIFICATION_WEB_NOTIFICATION_TRAY_H_