Add mojo structs for ScopedFD and ScopedHandle.

mojo/common/platform_handle.typemap

Index: mojo/common/platform_handle.typemap
diff --git a/mojo/common/platform_handle.typemap b/mojo/common/platform_handle.typemap
new file mode 100644
index 0000000000000000000000000000000000000000..6c78378b0ebb109f1ebff7624a9a734cec91254f
--- /dev/null
+++ b/mojo/common/platform_handle.typemap
@@ -0,0 +1,15 @@
+# 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.
+
+mojom = "//mojo/common/platform_handle.mojom"
+public_headers = [ "//mojo/common/platform_handle.h" ]
+traits_headers = [ "//mojo/common/common_custom_types_struct_traits.h" ]
+public_deps = [
+  "//mojo/common:struct_traits",
+]
+
+type_mappings = [
+  "mojo.common.mojom.FileDescriptor=mojo::common::ScopedFDForwarder[move_only,nullable_is_same_type]",
+  "mojo.common.mojom.WindowsHandle=mojo::common::ScopedHandleForwarder[move_only,nullable_is_same_type]",
+]