Refactor of QUIC's rtt storage and calculation to have a single RttStats

net/quic/congestion_control/pacing_sender.cc

Index: net/quic/congestion_control/pacing_sender.cc
diff --git a/net/quic/congestion_control/pacing_sender.cc b/net/quic/congestion_control/pacing_sender.cc
index 5bc5ac772c30a98c5561d49f419fe5db2a08de56..3a166670ccd9a30522027f1e7eee5ccd886f9546 100644
--- a/net/quic/congestion_control/pacing_sender.cc
+++ b/net/quic/congestion_control/pacing_sender.cc
@@ -126,10 +126,6 @@ void PacingSender::UpdateRtt(QuicTime::Delta rtt_sample) {
   sender_->UpdateRtt(rtt_sample);
 }
 
-QuicTime::Delta PacingSender::SmoothedRtt() const {
-  return sender_->SmoothedRtt();
-}
-
 QuicTime::Delta PacingSender::RetransmissionDelay() const {
   return sender_->RetransmissionDelay();
 }