Rename the aura_shell namespace to ash

ash/wm/shadow_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 ASH_WM_SHADOW_TYPES_H_
 #define ASH_WM_SHADOW_TYPES_H_
 #pragma once
 
 #include "ash/ash_export.h"
 
 namespace aura {
 class Window;
 }
 
-namespace aura_shell {
+namespace ash {
 namespace internal {
 
 // Different types of drop shadows that can be drawn under a window by the
 // shell.  Used as a value for the kShadowTypeKey property.
 enum ShadowType {
   // Starts at 0 due to the cast in GetShadowType().
   SHADOW_TYPE_NONE = 0,
   SHADOW_TYPE_RECTANGULAR,
 };
 
 ASH_EXPORT void SetShadowType(aura::Window* window,
                                      ShadowType shadow_type);
 ASH_EXPORT ShadowType GetShadowType(aura::Window* window);
 
 }  // namespace internal
-}  // namespace aura_shell
+}  // namespace ash
 
 #endif  // ASH_WM_SHADOW_TYPES_H_