mediaview: Add a typemap for arc::mojom::ChangeType.

components/arc/file_system/file_system_struct_traits.h

Index: components/arc/file_system/file_system_struct_traits.h
diff --git a/components/arc/file_system/file_system_struct_traits.h b/components/arc/file_system/file_system_struct_traits.h
new file mode 100644
index 0000000000000000000000000000000000000000..eae87efd1f4b5f08fe62dee4f903895146213b19
--- /dev/null
+++ b/components/arc/file_system/file_system_struct_traits.h
@@ -0,0 +1,23 @@
+// 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 COMPONENTS_ARC_FILE_SYSTEM_FILE_SYSTEM_STRUCT_TRAITS_H_
+#define COMPONENTS_ARC_FILE_SYSTEM_FILE_SYSTEM_STRUCT_TRAITS_H_
+
+#include "components/arc/common/file_system.mojom.h"
+#include "storage/browser/fileapi/watcher_manager.h"
+
+namespace mojo {
+
+template <>
+struct EnumTraits<arc::mojom::ChangeType, storage::WatcherManager::ChangeType> {
+  static arc::mojom::ChangeType ToMojom(
+      storage::WatcherManager::ChangeType type);
+  static bool FromMojom(arc::mojom::ChangeType mojom_type,
+                        storage::WatcherManager::ChangeType* type);
+};
+
+}  // namespace mojo
+
+#endif  // COMPONENTS_ARC_FILE_SYSTEM_FILE_SYSTEM_STRUCT_TRAITS_H_