URLRequest::status() lets a consumer get a preview of a status that it may not yet have been notified of, which leads to things like issue 469156.  I think it's safest to just remove he accessor and pass the result to NetworkDelegate/URLRequest::Delegate methods that need to know the state of the request.  This will probably be a pretty good size refactor.  Issue 490311 should probably be tackled first, to remove the difference between URLRequestStatus::CANCELLED and URLRequestStatus::FAILED with net::ERR_ABORTED.