Add mojo structs for ScopedFD and ScopedHandle.

mojo/common/common_custom_types_struct_traits_posix.h

Index: mojo/common/common_custom_types_struct_traits_posix.h
diff --git a/mojo/common/common_custom_types_struct_traits_posix.h b/mojo/common/common_custom_types_struct_traits_posix.h
new file mode 100644
index 0000000000000000000000000000000000000000..ac7d95230d57e981df8607a9794f10d781d00349
--- /dev/null
+++ b/mojo/common/common_custom_types_struct_traits_posix.h
@@ -0,0 +1,27 @@
+// Copyright 2016 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 MOJO_COMMON_COMMON_CUSTOM_TYPES_STRUCT_TRAITS_POSIX_H_
+#define MOJO_COMMON_COMMON_CUSTOM_TYPES_STRUCT_TRAITS_POSIX_H_
+
+#include "base/files/scoped_file.h"
+#include "mojo/common/mojo_common_export.h"
+#include "mojo/common/platform_handle.mojom-shared.h"
+
+namespace mojo {
+
+template <>
+struct StructTraits<common::mojom::FileDescriptorDataView, base::ScopedFD> {
+  static bool IsNull(const base::ScopedFD& fd) { return !fd.is_valid(); }
+
+  static void SetToNull(base::ScopedFD* fd) { *fd = base::ScopedFD(); }
+
+  static mojo::ScopedHandle wrapped_handle(base::ScopedFD& fd);
+  static bool Read(common::mojom::FileDescriptorDataView data,
+                   base::ScopedFD* fd);
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_COMMON_COMMON_CUSTOM_TYPES_STRUCT_TRAITS_POSIX_H_