chromeos: Move files in //ash/common to //ash

ash/common/wm/fullscreen_window_finder.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_FULLSCREEN_WINDOW_FINDER_H_
-#define ASH_COMMON_WM_FULLSCREEN_WINDOW_FINDER_H_
-
-#include "ash/ash_export.h"
-
-namespace ash {
-
-class WmWindow;
-
-namespace wm {
-
-// Returns the topmost window or one of its transient parents, if any of them
-// are in fullscreen mode. This searches for a window in the root of |context|.
-ASH_EXPORT WmWindow* GetWindowForFullscreenMode(WmWindow* context);
-
-}  // namespace wm
-}  // namespace ash
-
-#endif  // ASH_COMMON_WM_FULLSCREEN_WINDOW_FINDER_H_