RecordPingRTTHistogram 2439 net/spdy/spdy_session.cc   RecordPingRTTHistogram(time_func_() - last_ping_sent_time_);
RecordPingRTTHistogram 2738 net/spdy/spdy_session.cc     RecordPingRTTHistogram(base::TimeDelta::Max());
RecordPingRTTHistogram  726 net/spdy/spdy_session.h   void RecordPingRTTHistogram(base::TimeDelta duration);