QUIC test only change to add track the observed loss rate in

net/quic/congestion_control/send_algorithm_simulator.cc

Index: net/quic/congestion_control/send_algorithm_simulator.cc
diff --git a/net/quic/congestion_control/send_algorithm_simulator.cc b/net/quic/congestion_control/send_algorithm_simulator.cc
index 2e6bb23ad22d1ddb7033810b712cb8f7afddaac0..5c55f5b5d69d225486d7daefe22ba0592924bc76 100644
--- a/net/quic/congestion_control/send_algorithm_simulator.cc
+++ b/net/quic/congestion_control/send_algorithm_simulator.cc
@@ -34,7 +34,8 @@ SendAlgorithmSimulator::Sender::Sender(SendAlgorithmInterface* send_algorithm,
       min_cwnd(100000),
       max_cwnd_drop(0),
       last_cwnd(0),
-      last_transfer_bandwidth(QuicBandwidth::Zero()) {}
+      last_transfer_bandwidth(QuicBandwidth::Zero()),
+      last_transfer_loss_rate(0) {}
 
 SendAlgorithmSimulator::SendAlgorithmSimulator(
     MockClock* clock,
@@ -268,10 +269,13 @@ void SendAlgorithmSimulator::HandlePendingAck(Transfer* transfer) {
 
   sender->RecordStats();
   transfer->bytes_acked += acked_packets.size() * kPacketSize;
+  transfer->bytes_lost += lost_packets.size() * kPacketSize;
   if (transfer->bytes_acked >= transfer->num_bytes) {
     // Remove completed transfers and record transfer bandwidth.
     QuicTime::Delta transfer_time =
         clock_->Now().Subtract(transfer->start_time);
+    sender->last_transfer_loss_rate = static_cast<float>(transfer->bytes_lost) /
+        (transfer->bytes_lost + transfer->bytes_acked);
     sender->last_transfer_bandwidth =
         QuicBandwidth::FromBytesAndTimeDelta(transfer->num_bytes,
                                              transfer_time);