Shuffles and renames ash/common/wm classes

ash/common/wm_overview_mode_observer.h

 // Copyright 2016 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_COMMON_WM_WM_OVERVIEW_MODE_OBSERVER_H_
-#define ASH_COMMON_WM_WM_OVERVIEW_MODE_OBSERVER_H_
+#ifndef ASH_COMMON_WM_OVERVIEW_MODE_OBSERVER_H_
+#define ASH_COMMON_WM_OVERVIEW_MODE_OBSERVER_H_
 
 #include "ash/ash_export.h"
 
 namespace ash {
-namespace wm {
 
 class WmWindow;
 
 class ASH_EXPORT WmOverviewModeObserver {
  public:
   virtual void OnOverviewModeEnded() {}
 
  protected:
   virtual ~WmOverviewModeObserver() {}
 };
 
-}  // namespace wm
 }  // namespace ash
 
-#endif  // ASH_COMMON_WM_WM_OVERVIEW_MODE_OBSERVER_H_
+#endif  // ASH_COMMON_WM_OVERVIEW_MODE_OBSERVER_H_