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

net/quic/quic_sent_packet_manager_interface.h

 // Copyright 2016 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.
 
 #ifndef NET_QUIC_QUIC_SENT_PACKET_MANAGER_INTERFACE_H_
 #define NET_QUIC_QUIC_SENT_PACKET_MANAGER_INTERFACE_H_
 
 #include "base/macros.h"
 #include "net/quic/quic_protocol.h"
 #include "net/quic/quic_sustained_bandwidth_recorder.h"
@@ skipping 122 matching lines @@
   virtual const QuicTime GetRetransmissionTime() const = 0;
 
   // Returns the rtt stats of the default path.
   virtual const RttStats* GetRttStats() const = 0;
 
   // Returns the estimated bandwidth on default path calculated by the
   // congestion algorithm.
   virtual QuicBandwidth BandwidthEstimate() const = 0;
 
   // Returns the sustained bandwidth recorder on the default path.
-  virtual const QuicSustainedBandwidthRecorder& SustainedBandwidthRecorder()
+  virtual const QuicSustainedBandwidthRecorder* SustainedBandwidthRecorder()
       const = 0;
 
   // Returns the size of the current congestion window on default path in number
   // of kDefaultTCPMSS-sized segments.
   virtual QuicPacketCount GetCongestionWindowInTcpMss() const = 0;
 
   // Determines the number of packets of length |max_packet_length| which fit in
   // the congestion windows for all paths, and returns the max number of packets
   // across all paths.
   virtual QuicPacketCount EstimateMaxPacketsInFlight(
@@ skipping 34 matching lines @@
 
   // These two methods return the consecutive RTO or TLP count of the default
   // path.
   virtual size_t GetConsecutiveRtoCount() const = 0;
   virtual size_t GetConsecutiveTlpCount() const = 0;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_SENT_PACKET_MANAGER_INTERFACE_H_