Keep dedicated layers for hiding animation

ui/views/corewm/window_animations.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_COREWM_WINDOW_ANIMATIONS_H_
 #define UI_VIEWS_COREWM_WINDOW_ANIMATIONS_H_
 
 #include <vector>
 
 #include "ui/views/views_export.h"
@@ skipping 70 matching lines @@
     aura::Window* window,
     float position);
 
 // Creates an ImplicitAnimationObserver that takes ownership of the layers
 // associated with a Window so that the animation can continue after the Window
 // has been destroyed.
 // The returned object deletes itself when the animations are done.
 VIEWS_EXPORT ui::ImplicitAnimationObserver* CreateHidingWindowAnimationObserver(
     aura::Window* window);
 
+// Detach the existing layer and recreate the new layer for the window
+// if there is a hiding animation in progress. This is used to keep the
+// hiding animation visible on top of active windows. Returns NULL if there
+// is no hiding animation in progress.
+VIEWS_EXPORT ui::Layer* DetachHidingAnimationLayer(aura::Window* window);
+
 // Returns false if the |window| didn't animate.
 VIEWS_EXPORT bool AnimateOnChildWindowVisibilityChanged(aura::Window* window,
                                                         bool visible);
 VIEWS_EXPORT bool AnimateWindow(aura::Window* window, WindowAnimationType type);
 
 // Returns true if window animations are disabled for |window|. Window
 // animations are enabled by default. If |window| is NULL, this just checks
 // if the global flag disabling window animations is present.
 VIEWS_EXPORT bool WindowAnimationsDisabled(aura::Window* window);
 
 }  // namespace corewm
 }  // namespace views
 
 #endif  // UI_VIEWS_COREWM_WINDOW_ANIMATIONS_H_