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

ash/host/root_window_transformer.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 UI_AURA_ROOT_WINDOW_TRANSFORMER_H_
-#define UI_AURA_ROOT_WINDOW_TRANSFORMER_H_
+#ifndef ASH_HOST_ROOT_WINDOW_TRANSFORMER_H_
+#define ASH_HOST_ROOT_WINDOW_TRANSFORMER_H_
 
-#include "ui/aura/aura_export.h"
+#include "ash/ash_export.h"
 
 namespace gfx {
 class Insets;
 class Rect;
 class Size;
 class Transform;
 }
 
-namespace aura {
+namespace ash {
 
 // RootWindowTransformer controls how RootWindow should be placed and
 // transformed inside the host window.
-class AURA_EXPORT RootWindowTransformer {
+class ASH_EXPORT RootWindowTransformer {
  public:
   virtual ~RootWindowTransformer() {}
 
   // Returns the transform the root window in DIP.
   virtual gfx::Transform GetTransform() const = 0;
 
   // Returns the inverse of the transform above. This method is to
   // provie an accurate inverse of the transform because the result of
   // |gfx::Transform::GetInverse| may contains computational error.
   virtual gfx::Transform GetInverseTransform() const = 0;
 
   // Returns the root window's bounds for given host window size in DIP.
   // This is necessary to handle the case where the root window's size
   // is bigger than the host window. (Screen magnifier for example).
   virtual gfx::Rect GetRootWindowBounds(const gfx::Size& host_size) const = 0;
 
   // Returns the insets that specifies the effective area of
   // the host window.
   virtual gfx::Insets GetHostInsets() const = 0;
 };
 
-}  // namespace aura
+}  // namespace ash
 
-#endif  // UI_AURA_ROOT_WINDOW_TRANSFORMER_H_
+#endif  // ASH_HOST_ROOT_WINDOW_TRANSFORMER_H_