Mojo C++ bindings: support sync methods - part 1.

mojo/public/cpp/bindings/lib/interface_endpoint_client.cc

Index: mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
diff --git a/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc b/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
index 79c25b51a05ea28a93e43e64c668286b4b58bda0..0063bff2dd48b30427b5586c70d7121d589e53ca 100644
--- a/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
+++ b/mojo/public/cpp/bindings/lib/interface_endpoint_client.cc
@@ -161,6 +161,13 @@ bool InterfaceEndpointClient::AcceptWithResponder(Message* message,
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(message->has_flag(kMessageExpectsResponse));
 
+  // TODO(yzshen): Sync method call using assoicated interfaces or master
+  // interfaces that serve associated interfaces hasn't been supported yet.
+  if (message->has_flag(kMessageIsSync)) {
+    NOTIMPLEMENTED();
+    return false;
+  }
+
   if (encountered_error_)
     return false;