mash: Remove StatusAreaWidget references from system tray classes

ash/system/status_area_widget.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_STATUS_AREA_WIDGET_H_
 #define ASH_SYSTEM_STATUS_AREA_WIDGET_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 #include "ash/common/shelf/shelf_types.h"
@@ skipping 21 matching lines @@
   // Creates the SystemTray, WebNotificationTray and LogoutButtonTray.
   void CreateTrayViews();
 
   // Destroys the system tray and web notification tray. Called before
   // tearing down the windows to avoid shutdown ordering issues.
   void Shutdown();
 
   // Update the alignment of the widget and tray views.
   void SetShelfAlignment(ShelfAlignment alignment);
 
-  // Set the visibility of system notifications.
-  void SetHideSystemNotifications(bool hide);
-
   // Called by the client when the login status changes. Caches login_status
   // and calls UpdateAfterLoginStatusChange for the system tray and the web
   // notification tray.
   void UpdateAfterLoginStatusChange(LoginStatus login_status);
 
   StatusAreaWidgetDelegate* status_area_widget_delegate() {
     return status_area_widget_delegate_;
   }
   SystemTray* system_tray() { return system_tray_; }
   WebNotificationTray* web_notification_tray() {
@@ skipping 42 matching lines @@
   LoginStatus login_status_;
 
   WmShelf* wm_shelf_;
 
   DISALLOW_COPY_AND_ASSIGN(StatusAreaWidget);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_STATUS_AREA_WIDGET_H_