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

ash/system/brightness/tray_brightness.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/brightness/tray_brightness.h"
 
 #include "ash/accelerators/accelerator_controller.h"
 #include "ash/shell.h"
 #include "ash/system/brightness/brightness_control_delegate.h"
 #include "ash/system/tray/system_tray_delegate.h"
@@ skipping 166 matching lines @@
 void TrayBrightness::DestroyDefaultView() {
   if (is_default_view_)
     brightness_view_.reset();
 }
 
 void TrayBrightness::DestroyDetailedView() {
   if (!is_default_view_)
     brightness_view_.reset();
 }
 
+void TrayBrightness::UpdateAfterLoginStatusChange(user::LoginStatus status) {
+}
+
 void TrayBrightness::OnBrightnessChanged(double percent, bool user_initiated) {
   current_percent_ = percent;
   got_current_percent_ = true;
 
   if (brightness_view_.get())
     brightness_view_->SetBrightnessPercent(percent);
   if (!user_initiated)
     return;
 
   if (brightness_view_.get())
     SetDetailedViewCloseDelay(kTrayPopupAutoCloseDelayInSeconds);
   else
     PopupDetailedView(kTrayPopupAutoCloseDelayInSeconds, false);
 }
 
 }  // namespace internal
 }  // namespace ash