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

ash/wm/overview/scoped_transform_overview_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_SCOPED_TRANSFORM_OVERVIEW_WINDOW_H_
 #define ASH_WM_OVERVIEW_SCOPED_TRANSFORM_OVERVIEW_WINDOW_H_
 
 #include "base/compiler_specific.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
 
 namespace aura {
-class RootWindow;
 class Window;
 }
 
 namespace ui {
 class Layer;
 }
 
 namespace views {
 class Widget;
 }
@@ skipping 40 matching lines @@
   // destroyed. This resets the internal window pointer to avoid calling
   // anything on the window at destruction time.
   void OnWindowDestroyed();
 
   // Prepares for overview mode by doing any necessary actions before entering.
   virtual void PrepareForOverview();
 
   // Sets |transform| on the window and a copy of the window if the target
   // |root_window| is not the window's root window. If |animate| the transform
   // is animated in, otherwise it is immediately applied.
-  void SetTransform(aura::RootWindow* root_window,
+  void SetTransform(aura::Window* root_window,
                     const gfx::Transform& transform,
                     bool animate);
 
   aura::Window* window() const { return window_; }
 
  private:
   // Applies the |transform| to the overview window and all of its transient
   // children using animations. If |animate| the transform is animated in,
   // otherwise it is applied immediately.
   void SetTransformOnWindowAndTransientChildren(const gfx::Transform& transform,
@@ skipping 20 matching lines @@
 
   // The original transform of the window before entering overview mode.
   gfx::Transform original_transform_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedTransformOverviewWindow);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_OVERVIEW_SCOPED_TRANSFORM_OVERVIEW_WINDOW_H_