Add WindowPinType property on arua::Window

ash/public/cpp/window_pin_type.cc

Index: ash/public/cpp/window_pin_type.cc
diff --git a/ash/public/cpp/window_pin_type.cc b/ash/public/cpp/window_pin_type.cc
new file mode 100644
index 0000000000000000000000000000000000000000..48cd467603c244d9718193704d48c35553fe30e4
--- /dev/null
+++ b/ash/public/cpp/window_pin_type.cc
@@ -0,0 +1,17 @@
+// 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_pin_type.h"
+
+#include "ash/public/interfaces/window_pin_type.mojom.h"
+
+namespace ash {
+
+bool IsValidWindowPinType(int64_t value) {
+  return value == int64_t(ash::mojom::WindowPinType::NONE) ||
+         value == int64_t(ash::mojom::WindowPinType::PINNED) ||
+         value == int64_t(ash::mojom::WindowPinType::TRUSTED_PINNED);
+}
+
+}  // namespace ash