unsigned long long PerformanceTiming::domainLookupStart() const {
ResourceLoadTiming* timing = resourceLoadTiming();
if (!timing)
return fetchStart();
// This will be zero when a DNS request is not performed. Rather than
// exposing a special value that indicates no DNS, we "backfill" with
// fetchStart.
double dnsStart = timing->dnsStart();
if (dnsStart == 0.0)
return fetchStart();
return monotonicTimeToIntegerMilliseconds(dnsStart);
}
