Make GetRootWindow() return a Window instead of a RootWindow.

ash/touch/touch_observer_hud.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 ASH_TOUCH_TOUCH_OBSERVER_HUD_H_
 #define ASH_TOUCH_TOUCH_OBSERVER_HUD_H_
 
 #include "ash/ash_export.h"
 #include "ash/display/display_controller.h"
 #include "ui/events/event_handler.h"
@@ skipping 62 matching lines @@
 #endif  // defined(OS_CHROMEOS)
 
   // Overriden form DisplayController::Observer.
   virtual void OnDisplayConfigurationChanging() OVERRIDE;
   virtual void OnDisplayConfigurationChanged() OVERRIDE;
 
  private:
   friend class TouchHudTest;
 
   const int64 display_id_;
-  aura::RootWindow* root_window_;
+  aura::Window* root_window_;
 
   views::Widget* widget_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchObserverHUD);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_TOUCH_TOUCH_OBSERVER_HUD_H_