Land Recent QUIC Changes.

net/quic/congestion_control/inter_arrival_probe.cc

Index: net/quic/congestion_control/inter_arrival_probe.cc
diff --git a/net/quic/congestion_control/inter_arrival_probe.cc b/net/quic/congestion_control/inter_arrival_probe.cc
index 6d3af3208fe1151dbaa691d42d76481b4cbf0cb9..9f4c90cd42cd18b393cfedd14c8fc2ce302fd033 100644
--- a/net/quic/congestion_control/inter_arrival_probe.cc
+++ b/net/quic/congestion_control/inter_arrival_probe.cc
@@ -51,6 +51,12 @@ void InterArrivalProbe::OnAcknowledgedPacket(QuicByteCount bytes) {
   }
 }
 
+void InterArrivalProbe::OnRetransmissionTimeout() {
+  if (!estimate_available_) {
+    unacked_data_ = 0;
+  }
+}
+
 QuicByteCount InterArrivalProbe::GetAvailableCongestionWindow() {
   if (estimate_available_) {
     return 0;