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

ash/system/power/tray_power.cc

 // 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.
 
 #include "ash/system/power/tray_power.h"
 
 #include "ash/shell.h"
 #include "ash/system/date/date_view.h"
 #include "ash/system/power/power_supply_status.h"
 #include "ash/system/tray/system_tray_delegate.h"
@@ skipping 225 matching lines @@
 }
 
 void TrayPower::DestroyDefaultView() {
   date_.reset();
   power_.reset();
 }
 
 void TrayPower::DestroyDetailedView() {
 }
 
+void TrayPower::UpdateAfterLoginStatusChange(user::LoginStatus status) {
+}
+
 void TrayPower::OnPowerStatusChanged(const PowerSupplyStatus& status) {
   if (power_tray_.get())
     power_tray_->UpdatePowerStatus(status);
   if (power_.get())
     power_->UpdatePowerStatus(status);
 }
 
 }  // namespace internal
 }  // namespace ash