void RenderThreadImpl::WidgetRestored() {
  DCHECK_GT(hidden_widget_count_, 0);
  hidden_widget_count_--;

  if (!GetContentClient()->renderer()->RunIdleHandlerWhenWidgetsHidden()) {
    return;
  }

  ScheduleIdleHandler(kLongIdleHandlerDelayMs);
}

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.