For c++, Generate enum classes instead of enum from mojom.

mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl

Index: mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
index 53b212653eb646efc5ee95b399ae31658c29d959..d5bdcfc651923c113f00deb567fbb82d91944455 100644
--- a/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
@@ -78,6 +78,11 @@ void SerializeUnion_({{union.name}}* input, mojo::internal::Buffer* buf,
                 &result->data.f_{{field.name}});
         mojo::internal::InterfacePointerToData(
             input_acc.data()->{{field.name}}->Pass(), {{field.name}});
+{%    elif field.kind|is_enum_kind %}
+        result->data.f_{{field.name}} = 
+          static_cast<typename std::underlying_type<

[viettrungluu, 2015/10/01 17:49:55]

"

[johngro, 2015/10/02 00:49:04]

Done.

+            {{field.kind|cpp_wrapper_type}}>::type>(
+              input_acc.data()->{{field.name}});
 {%    else %}
         result->data.f_{{field.name}} = input_acc.data()->{{field.name}};
 {%-   endif %}