Introdcue AshWindowTreeHost and move ash/chrome specific code in WTH to ash.

ash/display/mirror_window_controller.h

 // Copyright (c) 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_DISPLAY_MIRROR_WINDOW_CONTROLLER_H_
 #define ASH_DISPLAY_MIRROR_WINDOW_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "ui/aura/window_tree_host.h"
 #include "ui/aura/window_tree_host_observer.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/size.h"
 
 namespace aura {
-class RootWindowTransformer;
 class Window;
 }
 
 namespace ui {
 class Reflector;
 }
 
 namespace ash {
+class AshWindowTreeHost;
+class RootWindowTransformer;
 namespace test{
 class MirrorWindowTestApi;
 }
 
 namespace internal {
 class DisplayInfo;
 
 // An object that copies the content of the primary root window to a
 // mirror window. This also draws a mouse cursor as the mouse cursor
 // is typically drawn by the window system.
 class ASH_EXPORT MirrorWindowController : public aura::WindowTreeHostObserver {
  public:
   MirrorWindowController();
   virtual ~MirrorWindowController();
 
   // Updates the root window's bounds using |display_info|.
   // Creates the new root window if one doesn't exist.
   void UpdateWindow(const DisplayInfo& display_info);
 
   // Same as above, but using existing display info
   // for the mirrored display.
   void UpdateWindow();
 
   // Close the mirror window.
   void Close();
 
   // aura::WindowTreeHostObserver overrides:
   virtual void OnHostResized(const aura::WindowTreeHost* host) OVERRIDE;
 
-  aura::WindowTreeHost* host() const { return host_.get(); }
+  AshWindowTreeHost* ash_host() const { return ash_host_.get(); }
 
  private:
   friend class test::MirrorWindowTestApi;
 
   // Creates a RootWindowTransformer for current display
   // configuration.
-  scoped_ptr<aura::RootWindowTransformer> CreateRootWindowTransformer() const;
+  scoped_ptr<RootWindowTransformer> CreateRootWindowTransformer() const;
 
-  scoped_ptr<aura::WindowTreeHost> host_;
+  scoped_ptr<AshWindowTreeHost> ash_host_;
   gfx::Size mirror_window_host_size_;
   scoped_refptr<ui::Reflector> reflector_;
 
   DISALLOW_COPY_AND_ASSIGN(MirrorWindowController);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DISPLAY_MIRROR_WINDOW_CONTROLLER_H_