Change QUIC's RTO implementation. Protected by FLAGS_quic_use_new_rto.

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 ceda073eb0eb6abf7b78a37f79b3ade1e1c3ab54..f1ebe87e0fa417b69d997a0acd530e0c9b93c4d6 100644
--- a/net/quic/quic_sent_packet_manager.h
+++ b/net/quic/quic_sent_packet_manager.h
@@ -290,6 +290,10 @@ class NET_EXPORT_PRIVATE QuicSentPacketManager {
   // Retransmits all crypto stream packets.
   void RetransmitCryptoPackets();
 
+  // Retransmits two packets for an RTO and removes any non-retransmittable
+  // packets from flight.
+  void RetransmitRtoPackets();
+
   // Retransmits all the packets and abandons by invoking a full RTO.
   void RetransmitAllPackets();
 
@@ -393,7 +397,7 @@ class NET_EXPORT_PRIVATE QuicSentPacketManager {
   size_t consecutive_tlp_count_;
   // Number of times the crypto handshake has been retransmitted.
   size_t consecutive_crypto_retransmission_count_;
-  // Number of pending transmissions of TLP or crypto packets.
+  // Number of pending transmissions of TLP, RTO, or crypto packets.
   size_t pending_timer_transmission_count_;
   // Maximum number of tail loss probes to send before firing an RTO.
   size_t max_tail_loss_probes_;