ash: Refresh the tray items, instead of recreating them, when login status changes.

ash/system/date/tray_date.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_DATE_TRAY_DATE_H_
 #define ASH_SYSTEM_DATE_TRAY_DATE_H_
 #pragma once
 
 #include "ash/system/date/clock_observer.h"
 #include "ash/system/tray/system_tray_item.h"
@@ skipping 12 matching lines @@
   virtual ~TrayDate();
 
  private:
   // Overridden from SystemTrayItem.
   virtual views::View* CreateTrayView(user::LoginStatus status) OVERRIDE;
   virtual views::View* CreateDefaultView(user::LoginStatus status) OVERRIDE;
   virtual views::View* CreateDetailedView(user::LoginStatus status) OVERRIDE;
   virtual void DestroyTrayView() OVERRIDE;
   virtual void DestroyDefaultView() OVERRIDE;
   virtual void DestroyDetailedView() OVERRIDE;
+  virtual void UpdateAfterLoginStatusChange(user::LoginStatus status) OVERRIDE;
 
   // Overridden from ClockObserver.
   virtual void OnDateFormatChanged() OVERRIDE;
   virtual void Refresh() OVERRIDE;
 
   scoped_ptr<tray::DateView> date_tray_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayDate);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_DATE_TRAY_DATE_H_