void RenderThreadImpl::AddEmbeddedWorkerRoute(int32 routing_id,
                                              IPC::Listener* listener) {
  AddRoute(routing_id, listener);
  if (devtools_agent_message_filter_.get()) {
    devtools_agent_message_filter_->AddEmbeddedWorkerRouteOnMainThread(
        routing_id);
  }
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.