Make HWNDMessageHandler subclass WindowImpl.

ui/views/win/fullscreen_handler.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_WIN_FULLSCREEN_HANDLER_H_
 #define UI_VIEWS_WIN_FULLSCREEN_HANDLER_H_
 
 #include <windows.h>
 
 #include <map>
 
 #include "base/basictypes.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace views {
 
-// TODO(beng): Temporary dependancy until fullscreen moves to
-//             HWNDMessageHandler.
-class Widget;
-
 class FullscreenHandler {
  public:
-  explicit FullscreenHandler(Widget* widget);
+  FullscreenHandler();
   ~FullscreenHandler();
 
   void SetFullscreen(bool fullscreen);
   void SetMetroSnap(bool metro_snap);
 
   gfx::Rect GetRestoreBounds() const;
 
   bool fullscreen() const { return fullscreen_; }
   bool metro_snap() const { return metro_snap_; }
 
+  void set_hwnd(HWND hwnd) { hwnd_ = hwnd; }
+
  private:
   // Information saved before going into fullscreen mode, used to restore the
   // window afterwards.
   struct SavedWindowInfo {
     bool maximized;
     LONG style;
     LONG ex_style;
     RECT window_rect;
   };
 
   void SetFullscreenImpl(bool fullscreen, bool for_metro);
 
-  Widget* widget_;
+  HWND hwnd_;
   bool fullscreen_;
   bool metro_snap_;
 
   // Saved window information from before entering fullscreen mode.
   // TODO(beng): move to private once GetRestoredBounds() moves onto Widget.
   SavedWindowInfo saved_window_info_;
 
   DISALLOW_COPY_AND_ASSIGN(FullscreenHandler);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_FULLSCREEN_HANDLER_H_