Mojo C++ bindings: provide data view for all object types.

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
@@ skipping 37 matching lines @@
 //
 //      Getters for fields of other types are called once.
 //
 //   2. A static Read() method to set the contents of a |T| instance from a
 //      |MojomType|DataView (e.g., if |MojomType| is test::Example, the data
 //      view will be test::ExampleDataView).
 //
 //        static bool Read(|MojomType|DataView data, T* output);
 //
 //      The generated |MojomType|DataView type provides a convenient,
-//      inexpensive view of a serialized struct's field data.
+//      inexpensive view of a serialized struct's field data. The caller
+//      guarantees that |!data.is_null()|.
 //
 //      Returning false indicates invalid incoming data and causes the message
 //      pipe receiving it to be disconnected. Therefore, you can do custom
 //      validation for |T| in this method.
 //
 //   3. [Optional] A static IsNull() method indicating whether a given |T|
 //      instance is null:
 //
 //        static bool IsNull(const T& input);
 //
@@ skipping 74 matching lines @@
 //
 //     static bool Read(FooDataView data, CustomFoo* output);
 //   };
 //
 template <typename MojomType, typename T>
 struct StructTraits;
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_STRUCT_TRAITS_H_