views: Some more layer change, and add/update some tests for layers.

ui/aura/window_delegate.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_WINDOW_DELEGATE_H_
 #define UI_AURA_WINDOW_DELEGATE_H_
 #pragma once
 
 #include "ui/aura/aura_export.h"
 #include "ui/gfx/native_widget_types.h"
@@ skipping 52 matching lines @@
   // Called from Window's destructor before OnWindowDestroyed and before the
   // children have been destroyed.
   virtual void OnWindowDestroying() = 0;
 
   // Called when the Window has been destroyed (i.e. from its destructor). This
   // is called after OnWindowDestroying and after the children have been
   // deleted.
   // The delegate can use this as an opportunity to delete itself if necessary.
   virtual void OnWindowDestroyed() = 0;
 
+  // Called when the visibility of a Window changed.
+  virtual void OnWindowVisibilityChanged(bool visible) = 0;
+
  protected:
   virtual ~WindowDelegate() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_DELEGATE_H_