change the way windows are parented when their parent is set to NULL.

ui/aura_shell/desktop_window.cc

 // Copyright (c) 2011 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 "ui/aura/desktop.h"
 #include "ui/aura/toplevel_window_container.h"
 #include "ui/aura/window.h"
 #include "ui/aura_shell/desktop_layout_manager.h"
 #include "ui/aura_shell/shell_factory.h"
 #include "ui/aura_shell/shell_window_ids.h"
 #include "views/widget/widget.h"
 
 namespace aura_shell {
 
 // Creates each of the special window containers that holds windows of various
 // types in the shell UI. They are added to |containers| from back to front in
 // the z-index.
 void CreateSpecialContainers(aura::Window::Windows* containers) {
   aura::Window* background_container = new aura::Window(NULL);
   background_container->set_id(
       internal::kShellWindowId_DesktopBackgroundContainer);
   containers->push_back(background_container);
 
-  aura::Window* default_container = new aura::internal::ToplevelWindowContainer;
+  aura::Window* default_container = new aura::ToplevelWindowContainer;
   default_container->set_id(internal::kShellWindowId_DefaultContainer);
-  aura::Desktop::GetInstance()->set_default_parent(default_container);
   containers->push_back(default_container);
 
-  aura::Window* always_on_top_container =
-      new aura::internal::ToplevelWindowContainer;
+  aura::Window* always_on_top_container = new aura::ToplevelWindowContainer;
   always_on_top_container->set_id(
       internal::kShellWindowId_AlwaysOnTopContainer);
   containers->push_back(always_on_top_container);
 
   aura::Window* launcher_container = new aura::Window(NULL);
   launcher_container->set_id(internal::kShellWindowId_LauncherContainer);
   containers->push_back(launcher_container);
 
   aura::Window* lock_container = new aura::Window(NULL);
   lock_container->set_stops_event_propagation(true);
@@ skipping 35 matching lines @@
       internal::kShellWindowId_StatusContainer)->AddChild(
           status_area->GetNativeView());
 
   desktop_layout->set_background_widget(desktop_background);
   desktop_layout->set_launcher_widget(launcher);
   desktop_layout->set_status_area_widget(status_area);
 }
 
 }  // namespace aura_shell