Move Aura to UI subdir.

ui/gfx/native_widget_types.h

 // Copyright (c) 2011 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_GFX_NATIVE_WIDGET_TYPES_H_
 #define UI_GFX_NATIVE_WIDGET_TYPES_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "ui/base/ui_export.h"
@@ skipping 19 matching lines @@
 //     specific typedef.
 //
 //   NativeImage: The platform-specific image type used for drawing UI elements
 //     in the browser.
 //
 // The name 'View' here meshes with OS X where the UI elements are called
 // 'views' and with our Chrome UI code where the elements are also called
 // 'views'.
 
 #if defined(USE_AURA)
-#include "aura/window.h"
+namespace aura {
+class Window;
+}
 #endif
 #if defined(OS_WIN)
 #include <windows.h>  // NOLINT
 typedef struct HFONT__* HFONT;
 struct IAccessible;
 #elif defined(OS_MACOSX)
 struct CGContext;
 #ifdef __OBJC__
 @class NSFont;
 @class NSImage;
@@ skipping 162 matching lines @@
 typedef unsigned long AcceleratedWidget;
 const AcceleratedWidget kNullAcceleratedWidget = 0;
 #else
 typedef void* AcceleratedWidget;
 const AcceleratedWidget kNullAcceleratedWidget = NULL;
 #endif
 
 }  // namespace gfx
 
 #endif  // UI_GFX_NATIVE_WIDGET_TYPES_H_