Rename the aura_shell namespace to ash

ash/wm/window_frame.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_WINDOW_FRAME_H_
 #define ASH_WM_WINDOW_FRAME_H_
 #pragma once
 
 #include "ash/ash_export.h"
 
-namespace aura_shell {
+namespace ash {
 
 // aura::Window property name for a pointer to the WindowFrame interface.
 ASH_EXPORT extern const char* const kWindowFrameKey;
 
 // Interface for clients implementing a window frame.  Implementors should
 // add a pointer to this interface to each aura::Window, using the key above.
 class ASH_EXPORT WindowFrame {
  public:
   virtual ~WindowFrame() {}
 
   // Called when the mouse enters or exits a top-level window.
   virtual void OnWindowHoverChanged(bool hovered) = 0;
 };
 
-}  // namespace aura_shell
+}  // namespace ash
 
 #endif  // ASH_WM_WINDOW_FRAME_H_