Rename the aura_shell namespace to ash

ash/shell.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_H_
 #define ASH_SHELL_H_
 #pragma once
 
 #include <utility>
 #include <vector>
@@ skipping 11 matching lines @@
 namespace aura {
 class EventFilter;
 class RootWindow;
 class Window;
 }
 namespace gfx {
 class Rect;
 class Size;
 }
 
-namespace aura_shell {
+namespace ash {
 
 class AcceleratorController;
 class Launcher;
 class ShellDelegate;
 
 namespace internal {
 class ActivationController;
 class AcceleratorFilter;
 class AppList;
 class DragDropController;
@@ skipping 94 matching lines @@
   scoped_ptr<internal::ShadowController> shadow_controller_;
   scoped_ptr<internal::TooltipController> tooltip_controller_;
 
   // An event filter that pre-handles global accelerators.
   scoped_ptr<internal::AcceleratorFilter> accelerator_filter_;
 
 
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };
 
-}  // namespace aura_shell
+}  // namespace ash
 
 #endif  // ASH_SHELL_H_