It is time.

ui/views/widget/window_reorderer.h

-// Copyright 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_VIEWS_WIDGET_WINDOW_REORDERER_H_
-#define UI_VIEWS_WIDGET_WINDOW_REORDERER_H_
-
-#include "base/compiler_specific.h"
-#include "base/memory/scoped_ptr.h"
-#include "ui/aura/window_observer.h"
-
-namespace aura {
-class Window;
-}
-
-namespace views {
-class View;
-
-// Class which reorders the widget's child windows which have an associated view
-// in the widget's view tree according the z-order of the views in the view
-// tree. Windows not associated to a view are stacked above windows with an
-// associated view. The child windows' layers are additionally reordered
-// according to the z-order of the associated views relative to views with
-// layers.
-class WindowReorderer : public aura::WindowObserver {
- public:
-  WindowReorderer(aura::Window* window, View* root_view);
-  virtual ~WindowReorderer();
-
-  // Explicitly reorder the children of |window_| (and their layers). This
-  // method should be called when the position of a view with an associated
-  // window changes in the view hierarchy. This method assumes that the
-  // child layers of |window_| which are owned by views are already in the
-  // correct z-order relative to each other and does no reordering if there
-  // are no views with an associated window.
-  void ReorderChildWindows();
-
- private:
-  // aura::WindowObserver overrides:
-  virtual void OnWindowAdded(aura::Window* new_window) override;
-  virtual void OnWillRemoveWindow(aura::Window* window) override;
-  virtual void OnWindowDestroying(aura::Window* window) override;
-
-  // The window and the root view of the native widget which owns the
-  // WindowReorderer.
-  aura::Window* parent_window_;
-  View* root_view_;
-
-  // Reorders windows as a result of the kHostViewKey being set on a child of
-  // |parent_window_|.
-  class AssociationObserver;
-  scoped_ptr<AssociationObserver> association_observer_;
-
-  DISALLOW_COPY_AND_ASSIGN(WindowReorderer);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_WIDGET_WINDOW_REORDERER_H_