Add a new RTO connection option to QUIC. Flag protected behind the

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index aaa982c907c9e10cb82866be6e856f6266fe1923..3f54f9b225b213b60cdd038dd311947f4a09c22c 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -100,6 +100,7 @@ QuicSentPacketManager::QuicSentPacketManager(
       pending_timer_transmission_count_(0),
       max_tail_loss_probes_(kDefaultMaxTailLossProbes),
       using_pacing_(false),
+      use_new_rto_(false),
       handshake_confirmed_(false) {
 }
 
@@ -154,6 +155,9 @@ void QuicSentPacketManager::SetFromConfig(const QuicConfig& config) {
   if (HasClientSentConnectionOption(config, kNTLP)) {
     max_tail_loss_probes_ = 0;
   }
+  if (HasClientSentConnectionOption(config, kNRTO)) {
+    use_new_rto_ = true;
+  }
   if (config.HasReceivedConnectionOptions() &&
       ContainsQuicTag(config.ReceivedConnectionOptions(), kTIME)) {
     loss_algorithm_.reset(LossDetectionInterface::Create(kTime));
@@ -216,7 +220,7 @@ void QuicSentPacketManager::OnIncomingAck(const QuicAckFrame& ack_frame,
   HandleAckForSentPackets(ack_frame);
   InvokeLossDetection(ack_receive_time);
   // Ignore losses in RTO mode.
-  if (FLAGS_quic_use_new_rto && consecutive_rto_count_ > 0) {
+  if (FLAGS_quic_use_new_rto && consecutive_rto_count_ > 0 && !use_new_rto_) {
     packets_lost_.clear();
   }
   MaybeInvokeCongestionEvent(rtt_updated, bytes_in_flight);
@@ -247,7 +251,9 @@ void QuicSentPacketManager::OnIncomingAck(const QuicAckFrame& ack_frame,
         // a spurious RTO from happening again.
         rtt_stats_.ExpireSmoothedMetrics();
       } else {
-        send_algorithm_->OnRetransmissionTimeout(true);
+        if (!use_new_rto_) {
+          send_algorithm_->OnRetransmissionTimeout(true);
+        }
       }
     }
     // Reset all retransmit counters any time a new packet is acked.