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

ash/wm/overview/window_selector_window.h

 // Copyright 2013 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_WM_OVERVIEW_WINDOW_SELECTOR_WINDOW_H_
 #define ASH_WM_OVERVIEW_WINDOW_SELECTOR_WINDOW_H_
 
 #include "ash/wm/overview/scoped_transform_overview_window.h"
 #include "ash/wm/overview/window_selector_item.h"
 #include "base/compiler_specific.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
-class RootWindow;
 class Window;
 }
 
 namespace ash {
 
 // This implements a window overview item with a single window which can be
 // selected.
 class WindowSelectorWindow : public WindowSelectorItem {
  public:
   WindowSelectorWindow(aura::Window* window);
   virtual ~WindowSelectorWindow();
 
   // WindowSelectorItem:
-  virtual aura::RootWindow* GetRootWindow() OVERRIDE;
+  virtual aura::Window* GetRootWindow() OVERRIDE;
   virtual aura::Window* TargetedWindow(const aura::Window* target) OVERRIDE;
   virtual void RestoreWindowOnExit(aura::Window* window) OVERRIDE;
   virtual aura::Window* SelectionWindow() OVERRIDE;
   virtual void RemoveWindow(const aura::Window* window) OVERRIDE;
   virtual bool empty() const OVERRIDE;
   virtual void PrepareForOverview() OVERRIDE;
-  virtual void SetItemBounds(aura::RootWindow* root_window,
+  virtual void SetItemBounds(aura::Window* root_window,
                              const gfx::Rect& target_bounds,
                              bool animate) OVERRIDE;
 
  private:
   ScopedTransformOverviewWindow transform_window_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowSelectorWindow);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_OVERVIEW_WINDOW_SELECTOR_WINDOW_H_