Rename the aura_shell namespace to ash

ash/shell_factory.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_SHELL_FACTORY_H_
 #define ASH_SHELL_FACTORY_H_
 #pragma once
 
 #include "ash/ash_export.h"
 
 namespace views {
 class Widget;
 }
 
 // Declarations of shell component factory functions.
 
-namespace aura_shell {
+namespace ash {
 
 namespace internal {
 views::Widget* CreateDesktopBackground();
 ASH_EXPORT views::Widget* CreateStatusArea();
 }  // namespace internal
 
-}  // namespace aura_shell
+}  // namespace ash
 
 
 #endif  // ASH_SHELL_FACTORY_H_