Shell related switches -> aura shell switches.

ui/aura/client/stacking_client.h

 // 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.
 
 #ifndef UI_AURA_CLIENT_STACKING_CLIENT_H_
 #define UI_AURA_CLIENT_STACKING_CLIENT_H_
 #pragma once
 
 #include "ui/aura/aura_export.h"
 
 namespace aura {
 class Window;
 namespace client {
 
+// A property key to store a client that handles window parenting. The type of
+// the value is |aura::client::StackingClient*|.
+AURA_EXPORT extern const char kRootWindowStackingClient[];
+
 // An interface implemented by an object that stacks windows.
 class AURA_EXPORT StackingClient {
  public:
   virtual ~StackingClient() {}
 
   // Called by the Window when its parent is set to NULL, returns the window
   // that |window| should be added to instead.
   virtual Window* GetDefaultParent(Window* window) = 0;
 };
 
 AURA_EXPORT void SetStackingClient(StackingClient* stacking_client);
 AURA_EXPORT StackingClient* GetStackingClient();
 
 }  // namespace client
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_STACKING_CLIENT_H_