Land Recent QUIC Changes.

net/quic/quic_sent_packet_manager.h

Index: net/quic/quic_sent_packet_manager.h
diff --git a/net/quic/quic_sent_packet_manager.h b/net/quic/quic_sent_packet_manager.h
index 2e75786119ac768c55be865214e01f7bff17149a..8d2a4512fed0e1828688e99c7372bfe564b6132b 100644
--- a/net/quic/quic_sent_packet_manager.h
+++ b/net/quic/quic_sent_packet_manager.h
@@ -290,7 +290,13 @@ class NET_EXPORT_PRIVATE QuicSentPacketManager {
   scoped_ptr<SendAlgorithmInterface> send_algorithm_;
   scoped_ptr<LossDetectionInterface> loss_algorithm_;
 
-  QuicPacketSequenceNumber largest_observed_;  // From the most recent ACK.
+  // The largest sequence number which we have sent and received an ACK for
+  // from the peer.
+  QuicPacketSequenceNumber largest_observed_;
+
+  // Tracks the first RTO packet.  If any packet before that packet gets acked,
+  // it indicates the RTO was spurious and should be reversed(F-RTO).
+  QuicPacketSequenceNumber first_rto_transmission_;
   // Number of times the RTO timer has fired in a row without receiving an ack.
   size_t consecutive_rto_count_;
   // Number of times the tail loss probe has been sent.