Remove root window from screen_ash

ash/screen_ash.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_SCREEN_ASH_H_
 #define ASH_SCREEN_ASH_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "ash/ash_export.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/screen_impl.h"
 
-namespace aura {
-class RootWindow;
-}
-
 namespace ash {
 
 // Aura implementation of gfx::Screen. Implemented here to avoid circular
 // dependencies.
 class ASH_EXPORT ScreenAsh : public gfx::ScreenImpl {
  public:
-  explicit ScreenAsh(aura::RootWindow* root_window);
+  ScreenAsh();
   virtual ~ScreenAsh();
 
   // Returns the bounds for maximized windows. Maximized windows trigger
   // auto-hiding the shelf.
   static gfx::Rect GetMaximizedWindowBounds(aura::Window* window);
 
   // Returns work area when a maximized window is not present.
   static gfx::Rect GetUnmaximizedWorkAreaBounds(aura::Window* window);
 
  protected:
   virtual gfx::Point GetCursorScreenPoint() OVERRIDE;
   virtual gfx::NativeWindow GetWindowAtCursorScreenPoint() OVERRIDE;
 
   virtual int GetNumMonitors() OVERRIDE;
   virtual gfx::Monitor GetMonitorNearestWindow(
       gfx::NativeView view) const OVERRIDE;
   virtual gfx::Monitor GetMonitorNearestPoint(
       const gfx::Point& point) const OVERRIDE;
   virtual gfx::Monitor GetPrimaryMonitor() const OVERRIDE;
 
  private:
-  aura::RootWindow* root_window_;
-
   DISALLOW_COPY_AND_ASSIGN(ScreenAsh);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SCREEN_ASH_H_