Support DWM switching....

chrome/views/widget.h

 // Copyright (c) 2006-2008 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 CHROME_VIEWS_WIDGET_H_
 #define CHROME_VIEWS_WIDGET_H_
 
 #if defined(OS_WIN)
 // TODO(maruel):  Remove once HWND is abstracted.
 #include <windows.h>
 #endif
 
 namespace gfx {
 class Rect;
 }
 
 namespace views {
 
+class Accelerator;
 class RootView;
 class TooltipManager;
-class Accelerator;
+class Window;
 
 ////////////////////////////////////////////////////////////////////////////////
 //
 // Widget interface
 //
 //   Widget is an abstract class that defines the API that should be implemented
 //   by a native window in order to host a view hierarchy.
 //
 //   Widget wraps a hierarchy of View objects (see view.h) that implement
 //   painting and flexible layout within the bounds of the Widget's window.
@@ skipping 38 matching lines @@
   // Returns the TooltipManager for this Widget. If this Widget does not support
   // tooltips, NULL is returned.
   virtual TooltipManager* GetTooltipManager() {
     return NULL;
   }
 
   // Returns the accelerator given a command id. Returns false if there is
   // no accelerator associated with a given id, which is a common condition.
   virtual bool GetAccelerator(int cmd_id,
                               Accelerator* accelerator) = 0;
+
+  // Returns the Widget as a Window, if such a conversion is possible, or NULL
+  // if it is not.
+  virtual Window* AsWindow() { return NULL; }
+  virtual const Window* AsWindow() const { return NULL; }
 };
 
 }  // namespace views
 
 #endif // CHROME_VIEWS_WIDGET_H_