Default to BBR congestion control for QUIC. Protected by

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 "net/quic/chromium/quic_utils_chromium.h"
@@ skipping 99 matching lines @@
     SetSendAlgorithm(kBBR);
   }
   if (config.HasClientRequestedIndependentOption(kRENO, perspective_)) {
     if (config.HasClientRequestedIndependentOption(kBYTE, perspective_)) {
       SetSendAlgorithm(kRenoBytes);
     } else {
       SetSendAlgorithm(kReno);
     }
   } else if (config.HasClientRequestedIndependentOption(kBYTE, perspective_)) {
     SetSendAlgorithm(kCubic);
+  } else if (FLAGS_quic_reloadable_flag_quic_default_to_bbr &&
+             config.HasClientRequestedIndependentOption(kQBIC, perspective_)) {
+    SetSendAlgorithm(kCubicBytes);
   } else if (FLAGS_quic_reloadable_flag_quic_enable_pcc &&
              config.HasClientRequestedIndependentOption(kTPCC, perspective_)) {
     SetSendAlgorithm(kPCC);
   }
 
   // The PCCSender implements its own version of pacing through the
   // SendAlgorithm::TimeUntilSend() function.  Do not wrap a
   // PacingSender around it, since wrapping a PacingSender around an
   // already paced SendAlgorithm produces a DCHECK.  TODO(fayang):
   // Change this if/when the PCCSender uses the PacingSender.
@@ skipping 834 matching lines @@
 const SendAlgorithmInterface* QuicSentPacketManager::GetSendAlgorithm() const {
   return send_algorithm_.get();
 }
 
 void QuicSentPacketManager::SetStreamNotifier(
     StreamNotifierInterface* stream_notifier) {
   unacked_packets_.SetStreamNotifier(stream_notifier);
 }
 
 }  // namespace net