Refactor Cubic congestion control to separate out PRR into a distinct

net/quic/congestion_control/tcp_cubic_sender.h

Index: net/quic/congestion_control/tcp_cubic_sender.h
diff --git a/net/quic/congestion_control/tcp_cubic_sender.h b/net/quic/congestion_control/tcp_cubic_sender.h
index c59172c01a0cd69d9b67da33e89dd602e42f8389..ae05ee25f9e6b1915177f2bfca176bee8349e447 100644
--- a/net/quic/congestion_control/tcp_cubic_sender.h
+++ b/net/quic/congestion_control/tcp_cubic_sender.h
@@ -13,6 +13,7 @@
 #include "net/base/net_export.h"
 #include "net/quic/congestion_control/cubic.h"
 #include "net/quic/congestion_control/hybrid_slow_start.h"
+#include "net/quic/congestion_control/prr_sender.h"
 #include "net/quic/congestion_control/send_algorithm_interface.h"
 #include "net/quic/quic_bandwidth.h"
 #include "net/quic/quic_connection_stats.h"
@@ -79,14 +80,10 @@ class NET_EXPORT_PRIVATE TcpCubicSender : public SendAlgorithmInterface {
   void MaybeIncreaseCwnd(QuicPacketSequenceNumber acked_sequence_number,
                          QuicByteCount bytes_in_flight);
   bool IsCwndLimited(QuicByteCount bytes_in_flight) const;
-  // Methods for isolating PRR from the rest of TCP Cubic.
-  void PrrOnPacketLost(QuicByteCount bytes_in_flight);
-  void PrrOnPacketAcked(QuicByteCount acked_bytes);
-  QuicTime::Delta PrrTimeUntilSend(QuicByteCount bytes_in_flight) const;
-
 
   HybridSlowStart hybrid_slow_start_;
   Cubic cubic_;
+  PrrSender prr_;
   const RttStats* rtt_stats_;
   QuicConnectionStats* stats_;
 
@@ -99,14 +96,6 @@ class NET_EXPORT_PRIVATE TcpCubicSender : public SendAlgorithmInterface {
   // ACK counter for the Reno implementation.
   uint64 congestion_window_count_;
 
-  // Bytes sent and acked since the last loss event.  Used for PRR.
-  QuicByteCount prr_out_;
-  QuicByteCount prr_delivered_;
-  size_t ack_count_since_loss_;
-
-  // The congestion window before the last loss event.
-  QuicByteCount bytes_in_flight_before_loss_;
-
   // Track the largest packet that has been sent.
   QuicPacketSequenceNumber largest_sent_sequence_number_;