Add a merely pass-through QuicMultipathSentPacketManager. Protected behind blocked flag FLAGS_quic_…

net/quic/quic_sent_packet_manager.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_sent_packet_manager.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 879 matching lines @@
 const RttStats* QuicSentPacketManager::GetRttStats() const {
   return &rtt_stats_;
 }
 
 QuicBandwidth QuicSentPacketManager::BandwidthEstimate() const {
   // TODO(ianswett): Remove BandwidthEstimate from SendAlgorithmInterface
   // and implement the logic here.
   return send_algorithm_->BandwidthEstimate();
 }
 
-const QuicSustainedBandwidthRecorder&
+const QuicSustainedBandwidthRecorder*
 QuicSentPacketManager::SustainedBandwidthRecorder() const {
-  return sustained_bandwidth_recorder_;
+  return &sustained_bandwidth_recorder_;
 }
 
 QuicPacketCount QuicSentPacketManager::EstimateMaxPacketsInFlight(
     QuicByteCount max_packet_length) const {
   return send_algorithm_->GetCongestionWindow() / max_packet_length;
 }
 
 QuicPacketCount QuicSentPacketManager::GetCongestionWindowInTcpMss() const {
   return send_algorithm_->GetCongestionWindow() / kDefaultTCPMSS;
 }
@@ skipping 93 matching lines @@
 TransmissionInfo* QuicSentPacketManager::GetMutableTransmissionInfo(
     QuicPacketNumber packet_number) {
   return unacked_packets_.GetMutableTransmissionInfo(packet_number);
 }
 
 void QuicSentPacketManager::RemoveObsoletePackets() {
   unacked_packets_.RemoveObsoletePackets();
 }
 
 }  // namespace net