Allow congestion controller state to be accessed by the debug visitors.

net/quic/core/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/core/quic_sent_packet_manager.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/logging.h"
@@ skipping 1044 matching lines @@
 }
 
 void QuicSentPacketManager::RemoveObsoletePackets() {
   unacked_packets_.RemoveObsoletePackets();
 }
 
 void QuicSentPacketManager::OnApplicationLimited() {
   send_algorithm_->OnApplicationLimited(unacked_packets_.bytes_in_flight());
 }
 
+const SendAlgorithmInterface* QuicSentPacketManager::GetSendAlgorithm() const {
+  return send_algorithm_.get();
+}
+
 }  // namespace net