ash uber tray: Add a tray item for the user.

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/panel_window.h"
 #include "ash/system/tray/system_tray_item.h"
 #include "ash/wm/shadow_types.h"
 #include "base/logging.h"
@@ skipping 75 matching lines @@
       ++it) {
     (*it)->DestroyTrayView();
   }
 }
 
 void SystemTray::AddTrayItem(SystemTrayItem* item) {
   items_.push_back(item);
 
   views::View* tray_item = item->CreateTrayView();
   if (tray_item) {
-    AddChildView(tray_item);
+    AddChildViewAt(tray_item, 0);
     PreferredSizeChanged();
   }
 }
 
 void SystemTray::RemoveTrayItem(SystemTrayItem* item) {
   NOTIMPLEMENTED();
 }
 
 void SystemTray::ShowDetailedView(SystemTrayItem* item) {
   if (popup_)
@@ skipping 20 matching lines @@
     ShowItems(items_, false);
   return true;
 }
 
 void SystemTray::OnWidgetClosing(views::Widget* widget) {
   CHECK_EQ(popup_, widget);
   popup_ = NULL;
 }
 
 }  // namespace ash