Remove TransparentActivateWindowButton from Overview Mode

ash/wm/overview/transparent_activate_window_button_delegate.h

-// Copyright 2014 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.
-// A delegate that
-
-#ifndef ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_DELEGATE_H_
-#define ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_DELEGATE_H_
-
-#include "ash/ash_export.h"
-
-namespace ash {
-
-// A pure-virtual delegate that is used by the TransparentActivateWindowButton
-// to manipulate windows while in overview mode.
-class ASH_EXPORT TransparentActivateWindowButtonDelegate {
- public:
-  // Called when the TransparentActivateWindowButton was selected.
-  virtual void Select() = 0;
-
- protected:
-  TransparentActivateWindowButtonDelegate() {}
-  virtual ~TransparentActivateWindowButtonDelegate() {}
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(TransparentActivateWindowButtonDelegate);
-};
-
-}  // namespace ash
-
-#endif  // ASH_WM_OVERVIEW_TRANSPARENT_ACTIVATE_WINDOW_BUTTON_DELEGATE_H_