Add WindowPinType property on arua::Window

ash/public/cpp/window_pin_type.h

Index: ash/public/cpp/window_pin_type.h
diff --git a/ash/public/cpp/window_pin_type.h b/ash/public/cpp/window_pin_type.h
new file mode 100644
index 0000000000000000000000000000000000000000..8fe6905897f5bbf376ebef8049a9faf13ee16415
--- /dev/null
+++ b/ash/public/cpp/window_pin_type.h
@@ -0,0 +1,18 @@
+// 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_PIN_TYPE_H_
+#define ASH_PUBLIC_CPP_WINDOW_PIN_TYPE_H_
+
+#include <cstdint>
+
+#include "ash/public/cpp/ash_public_export.h"
+
+namespace ash {
+
+ASH_PUBLIC_EXPORT bool IsValidWindowPinType(int64_t value);
+
+}  // namespace ash
+
+#endif  // ASH_PUBLIC_CPP_WINDOW_PIN_TYPE_H_