[mojo] Support native types with mojom wire format

mojo/public/cpp/bindings/struct_traits.h

+// Copyright 2015 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_PUBLIC_CPP_BINDINGS_STRUCT_TRAITS_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_STRUCT_TRAITS_H_
+
+namespace mojo {
+
+// This must be specialized for any type |T| to be serialized/deserialized as
+// a mojom struct of type |MojomType|.
+//
+// Each specialization must implement a few things:
+//
+//   1. Static getters for each field in the Mojom type. These should be
+//      of the form:
+//
+//        static <return type> <field name>(const T&)
+//
+//      and should return a serializable form of the named field as extracted
+//      from the referenced |T| instance.
+//
+//   2. A static Read method to initialize a new |T| from a MojomType::Reader:
+//
+//        static bool Read(MojomType::Reader r, T* out);

[Jeffrey Yasskin, 2016/01/28 18:01:40]

Could you document whether a 'true' or 'false' return is a failure?

Also, is there documentation for the API of the Reader type? (I haven't looked
yet, so sorry if it's obvious.)

And, what's a "serializable form"?

+//
+//      The generated MojomType::Reader type provides a convenient, inexpensive
+//      view of a serialized struct's field data.
+//
+template <typename MojomType, typename T>
+struct StructTraits;
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_STRUCT_TRAITS_H_