It is time.

ui/aura/client/visibility_client.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_AURA_CLIENT_VISIBILITY_CLIENT_H_
-#define UI_AURA_CLIENT_VISIBILITY_CLIENT_H_
-
-#include "ui/aura/aura_export.h"
-
-namespace aura {
-class Window;
-namespace client {
-
-// An interface implemented by an object that manages the visibility of Windows'
-// layers as Window visibility changes.
-class AURA_EXPORT VisibilityClient {
- public:
-  // Called when |window|'s visibility is changing to |visible|. The implementor
-  // can decide whether or not to pass on the visibility to the underlying
-  // layer.
-  virtual void UpdateLayerVisibility(Window* window, bool visible) = 0;
-
- protected:
-  virtual ~VisibilityClient() {}
-};
-
-// Sets the VisibilityClient on the Window.
-AURA_EXPORT void SetVisibilityClient(Window* window, VisibilityClient* client);
-
-// Gets the VisibilityClient for the window. This will crawl up |window|'s
-// hierarchy until it finds one.
-AURA_EXPORT VisibilityClient* GetVisibilityClient(Window* window);
-
-}  // namespace clients
-}  // namespace aura
-
-#endif  // UI_AURA_CLIENT_VISIBILITY_CLIENT_H_