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

ash/public/cpp/window_properties.cc

Index: ash/public/cpp/window_properties.cc
diff --git a/ash/public/cpp/window_properties.cc b/ash/public/cpp/window_properties.cc
deleted file mode 100644
index e51444cbfc41b00c968c582d9242dde4e2adb648..0000000000000000000000000000000000000000
--- a/ash/public/cpp/window_properties.cc
+++ /dev/null
@@ -1,13 +0,0 @@
-// 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.
-
-#include "ash/public/cpp/window_properties.h"
-
-namespace ash {
-
-DEFINE_UI_CLASS_PROPERTY_KEY(bool, kPanelAttachedKey, true);
-
-DEFINE_UI_CLASS_PROPERTY_KEY(int32_t, kShelfItemTypeKey, TYPE_UNDEFINED);
-
-}  // namespace ash