The timing information curl returns is calculated based on the curl_ease_perform(), which is invoked in background thread. The real metrics should be started at the timing of request handler (CurlRequest) started timing.
Created attachment 349815 [details] PATCH responseEnd was implemented correctly. Also initial delay caused by the gap from main thread to curl thread was adjusted.
Created attachment 349819 [details] PATCH
Comment on attachment 349819 [details] PATCH Clearing flags on attachment: 349819 Committed r236029: <https://trac.webkit.org/changeset/236029>
All reviewed patches have been landed. Closing bug.
<rdar://problem/44475694>