Rename the aura_shell namespace to ash

ash/wm/workspace/workspace_observer.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_WORKSPACE_WORKSPACE_OBSERVER_H_
 #define ASH_WM_WORKSPACE_WORKSPACE_OBSERVER_H_
 #pragma once
 
 #include "ash/ash_export.h"
 
 namespace aura {
 class Window;
 }
 
-namespace aura_shell {
+namespace ash {
 namespace internal {
 class Workspace;
 class WorkspaceManager;
 
 // A class to observe changes in workspace state.
 class ASH_EXPORT WorkspaceObserver {
  public:
   // Invoked when |start| window is moved and inserted
   // at the |target| window's position by |WorkspaceManager::RotateWindow|.
   virtual void WindowMoved(WorkspaceManager* manager,
                            aura::Window* source,
                            aura::Window* target) = 0;
 
   // Invoked when the active workspace changes. |old| is
   // the old active workspace and can be NULL.
   virtual void ActiveWorkspaceChanged(WorkspaceManager* manager,
                                       Workspace* old) = 0;
  protected:
   virtual ~WorkspaceObserver() {}
 };
 
 }  // namespace internal
-}  // namespace aura_shell
+}  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_WORKSPACE_OBSERVER_H_