mash: improves browser frame decorations

ash/public/cpp/window_style.cc

+// 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_style.h"
+
+#include "ash/public/interfaces/window_style.mojom.h"
+
+namespace ash {
+
+bool IsValidWindowStyle(int32_t type) {
+  return type == static_cast<int32_t>(mojom::WindowStyle::DEFAULT) ||
+         type == static_cast<int32_t>(mojom::WindowStyle::BROWSER);
+}
+
+}  // namespace ash