Add a container window to host the desktop window hierarchy in AURA.

ui/views/widget/desktop_aura/desktop_native_widget_aura.h

 // 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.
 
 #ifndef UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_NATIVE_WIDGET_AURA_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_NATIVE_WIDGET_AURA_H_
 
 #include "base/memory/weak_ptr.h"
 #include "ui/aura/client/activation_change_observer.h"
 #include "ui/aura/client/activation_delegate.h"
@@ skipping 224 matching lines @@
   // Can we be made active?
   bool can_activate_;
 
   // Ownership passed to RootWindow on Init.
   DesktopRootWindowHost* desktop_root_window_host_;
 
   // The content of |root_window_|. WARNING: this may be NULL if deleted out
   // from under us.
   aura::Window* window_;
 
+  // Contains the content window defined above. Ensures that ZOrder changes
+  // occurring in the content window hierarchy don't affect the other children
+  // of the root window.
+  aura::Window* content_window_container_;
+
   internal::NativeWidgetDelegate* native_widget_delegate_;
 
   scoped_ptr<aura::client::StackingClient> stacking_client_;
 
   // Toplevel event filter which dispatches to other event filters.
   corewm::CompoundEventFilter* root_window_event_filter_;
 
   scoped_ptr<corewm::InputMethodEventFilter> input_method_event_filter_;
 
   scoped_ptr<DropHelper> drop_helper_;
@@ skipping 17 matching lines @@
   // Reorders child windows of |window_| associated with a view based on the
   // order of the associated views in the widget's view hierarchy.
   scoped_ptr<WindowReorderer> window_reorderer_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopNativeWidgetAura);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_NATIVE_WIDGET_AURA_H_