Add GetDebugState() in SendAlgorithmInterface().

net/quic/core/quic_sent_packet_manager.h

 // 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.
 
 #ifndef NET_QUIC_QUIC_SENT_PACKET_MANAGER_H_
 #define NET_QUIC_QUIC_SENT_PACKET_MANAGER_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 162 matching lines @@
       QuicByteCount max_packet_length) const override;
 
   // Returns the size of the current congestion window size in bytes.
   QuicByteCount GetCongestionWindowInBytes() const override;
 
   // Returns the size of the slow start congestion window in nume of 1460 byte
   // TCP segments, aka ssthresh.  Some send algorithms do not define a slow
   // start threshold and will return 0.
   QuicPacketCount GetSlowStartThresholdInTcpMss() const override;
 
+  // Returns debugging information about the state of the congestion controller.
+  std::string GetDebugState() const override;
+
   // No longer retransmit data for |stream_id|.
   void CancelRetransmissionsForStream(QuicStreamId stream_id) override;
 
   // Called when peer address changes and the connection migrates.
   void OnConnectionMigration(QuicPathId, PeerAddressChangeType type) override;
 
   bool IsHandshakeConfirmed() const override;
 
   void SetDebugDelegate(DebugDelegate* debug_delegate) override;
 
@@ skipping 208 matching lines @@
   // Records bandwidth from server to client in normal operation, over periods
   // of time with no loss events.
   QuicSustainedBandwidthRecorder sustained_bandwidth_recorder_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicSentPacketManager);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_SENT_PACKET_MANAGER_H_