Revert of mash: Fix MusPropertyMirrorAsh for owned properties; add test.

ash/public/cpp/window_properties.h

-// Copyright 2017 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_PUBLIC_CPP_WINDOW_PROPERTIES_H_
-#define ASH_PUBLIC_CPP_WINDOW_PROPERTIES_H_
-
-#include <stdint.h>
-
-#include "ash/public/cpp/shelf_item_types.h"
-#include "ui/base/class_property.h"
-
-namespace aura {
-template <typename T>
-using WindowProperty = ui::ClassProperty<T>;
-}
-
-namespace ash {
-
-// Shell-specific window property keys for use by ash and its clients.
-
-// Alphabetical sort.
-
-// If true (and the window is a panel), it's attached to its shelf item.
-extern const aura::WindowProperty<bool>* const kPanelAttachedKey;
-
-// A property key to store the type of a window's shelf item.
-extern const aura::WindowProperty<int32_t>* const kShelfItemTypeKey;
-
-// Alphabetical sort.
-
-}  // namespace ash
-
-#endif  // ASH_PUBLIC_CPP_WINDOW_PROPERTIES_H_