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

ash/system/tray/system_tray.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/tray/system_tray.h"
 
 #include "ash/shell.h"
 #include "ash/shell/panel_window.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 480 matching lines @@
     bubble_->StartAutoCloseTimer(close_delay);
 }
 
 void SystemTray::UpdateAfterLoginStatusChange(user::LoginStatus login_status) {
   if (popup_)
     popup_->CloseNow();
 
   for (std::vector<SystemTrayItem*>::iterator it = items_.begin();
       it != items_.end();
       ++it) {
-    (*it)->DestroyTrayView();
+    (*it)->UpdateAfterLoginStatusChange(login_status);
   }
-  container_->RemoveAllChildViews(true);
 
-  for (std::vector<SystemTrayItem*>::iterator it = items_.begin();
-      it != items_.end();
-      ++it) {
-    views::View* view = (*it)->CreateTrayView(login_status);
-    if (view)
-      container_->AddChildViewAt(view, 0);
-  }
   SetVisible(true);
   PreferredSizeChanged();
 }
 
 void SystemTray::SetPaintsBackground(
       bool value,
       internal::BackgroundAnimator::ChangeType change_type) {
   hide_background_animator_.SetPaintsBackground(value, change_type);
 }
 
@@ skipping 109 matching lines @@
       popup_->Hide();
     }
   }
   return base::EVENT_CONTINUE;
 }
 
 void SystemTray::DidProcessEvent(const base::NativeEvent& event) {
 }
 
 }  // namespace ash