Mojo: abstract interface implementation from generated Stub classes

mojo/public/bindings/generators/cpp_templates/interface_definition.tmpl

 {%- set class_name = interface.name %}
 {%- set proxy_name = interface.name ~ "Proxy" %}
 
 {{proxy_name}}::{{proxy_name}}(mojo::MessageReceiver* receiver)
     : receiver_(receiver) {
 }
 
 {#--- Proxy definitions #}
 {%- macro params_list(method) %}
 {%-   for param in method.parameters -%}
@@ skipping 37 matching lines @@
 
   mojo::Message message;
   mojo::internal::EncodePointersAndHandles(params, &message.handles);
 
   message.data = builder.Finish();
 
   receiver_->Accept(&message);
 }
 {%- endfor %}
 
+{{class_name}}Stub::{{class_name}}Stub({{class_name}}* sink)
+    : sink_(sink) {
+}
+
 {#--- Stub definition #}
 {%- macro params(method) %}
 {%-   for param in method.parameters %}
 {%-     if param.kind|is_object_kind -%}
 mojo::internal::Wrap(params->{{param.name}}())
 {%-     elif param.kind|is_handle_kind -%}
 mojo::MakePassable(params->{{param.name}}()).Pass()
 {%-     else -%}
 params->{{param.name}}()
 {%-     endif -%}
 {%-     if not loop.last %}, {% endif %}
 {%-   endfor %}
 {%- endmacro %}
 
 bool {{class_name}}Stub::Accept(mojo::Message* message) {
   switch (message->data->header.name) {
 {%- for method in interface.methods %}
     case internal::k{{class_name}}_{{method.name}}_Name: {
       internal::{{class_name}}_{{method.name}}_Params_Data* params =
           reinterpret_cast<internal::{{class_name}}_{{method.name}}_Params_Data*>(
               message->data->payload);
 
       if (!mojo::internal::DecodePointersAndHandles(params, message))
         return false;
-      {{method.name}}({{params(method)}});
+      sink_->{{method.name}}({{params(method)}});
       mojo::internal::CloseHandles(params);
       break;
     }
 {%- endfor %}
   }
   return true;
 }