ResourceDispatcherHostImpl::~ResourceDispatcherHostImpl() {
  DCHECK(outstanding_requests_stats_map_.empty());
  DCHECK(g_resource_dispatcher_host);
  g_resource_dispatcher_host = NULL;
}

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.