It is time.

ui/aura/client/window_stacking_client.h

-// Copyright (c) 2013 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_WINDOW_STACKING_CLIENT_H_
-#define UI_AURA_CLIENT_WINDOW_STACKING_CLIENT_H_
-
-#include "base/basictypes.h"
-#include "base/memory/scoped_ptr.h"
-#include "ui/aura/aura_export.h"
-#include "ui/aura/window.h"
-
-namespace aura {
-namespace client {
-
-class AURA_EXPORT WindowStackingClient {
- public:
-  // Invoked from the various Window stacking functions. Allows the
-  // WindowStackingClient to alter the source, target and/or direction to stack.
-  // Returns true if stacking should continue; false if the stacking should not
-  // happen.
-  virtual bool AdjustStacking(Window** child,
-                              Window** target,
-                              Window::StackDirection* direction) = 0;
-
- protected:
-  virtual ~WindowStackingClient() {}
-};
-
-// Sets/gets the WindowStackingClient. This does *not* take ownership of
-// |client|. It is assumed the caller will invoke SetWindowStackingClient(NULL)
-// before deleting |client|.
-AURA_EXPORT void SetWindowStackingClient(WindowStackingClient* client);
-AURA_EXPORT WindowStackingClient* GetWindowStackingClient();
-
-}  // namespace client
-}  // namespace aura
-
-#endif  // UI_AURA_CLIENT_WINDOW_STACKING_CLIENT_H_