Mojo C++ bindings: allow StructTraits to return handle or interface types as value.

mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.h

Index: mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.h
diff --git a/mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.h b/mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.h
index a976f2c70677c43aaa295d6a71a78af670222e70..4550526d7bb5f263bd36034b55e3ea66905365f8 100644
--- a/mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.h
+++ b/mojo/public/cpp/bindings/tests/struct_with_traits_impl_traits.h
@@ -101,8 +101,8 @@ struct StructTraits<test::PassByValueStructWithTraits,
 
   // Fields in test::PassByValueStructWithTraits.
   // See src/mojo/public/interfaces/bindings/tests/struct_with_traits.mojom.
-  static ScopedHandle& f_handle(test::PassByValueStructWithTraitsImpl& value) {
-    return value.get_mutable_handle();
+  static ScopedHandle f_handle(test::PassByValueStructWithTraitsImpl& value) {
+    return std::move(value.get_mutable_handle());

[Peng, 2016/07/06 18:05:26]

Yes. This is what I need.

   }
 };