Moves common code in ash/wm/overview to ash/common/wm/overview

ash/wm/overview/scoped_overview_animation_settings.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_WM_OVERVIEW_SCOPED_OVERVIEW_ANIMATION_SETTINGS_H_
-#define ASH_WM_OVERVIEW_SCOPED_OVERVIEW_ANIMATION_SETTINGS_H_
-
-namespace ash {
-
-// ScopedOverviewAnimationSettings correctly configures the animation
-// settings for a WmWindow given an OverviewAnimationType.
-class ScopedOverviewAnimationSettings {
- public:
-  virtual ~ScopedOverviewAnimationSettings() {}
-};
-
-}  // namespace ash
-
-#endif  // ASH_WM_OVERVIEW_SCOPED_OVERVIEW_ANIMATION_SETTINGS_H_