void RenderThreadImpl::NotifyTimezoneChange() {
  NotifyTimezoneChangeOnThisThread();
  RenderThread::Get()->PostTaskToAllWebWorkers(
      base::Bind(&NotifyTimezoneChangeOnThisThread));
}

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.