Add a flag to enable QUIC's BBR congestion control by default instead of

net/quic/quic_connection.cc

 // Copyright (c) 2012 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_connection.h"
 
 #include <string.h>
 #include <sys/types.h>
 #include <algorithm>
 #include <iterator>
@@ skipping 210 matching lines @@
       timeout_alarm_(helper->CreateAlarm(new TimeoutAlarm(this))),
       ping_alarm_(helper->CreateAlarm(new PingAlarm(this))),
       packet_generator_(connection_id_, &framer_, random_generator_, this),
       idle_network_timeout_(
           QuicTime::Delta::FromSeconds(kDefaultInitialTimeoutSecs)),
       overall_connection_timeout_(QuicTime::Delta::Infinite()),
       time_of_last_received_packet_(clock_->ApproximateNow()),
       time_of_last_sent_new_packet_(clock_->ApproximateNow()),
       sequence_number_of_last_sent_packet_(0),
       sent_packet_manager_(
-          is_server, clock_, &stats_, kCubic,
+          is_server, clock_, &stats_,
+          FLAGS_quic_use_bbr_congestion_control ? kBBR : kCubic,
           FLAGS_quic_use_time_loss_detection ? kTime : kNack),
       version_negotiation_state_(START_NEGOTIATION),
       is_server_(is_server),
       connected_(true),
       peer_ip_changed_(false),
       peer_port_changed_(false),
       self_ip_changed_(false),
       self_port_changed_(false) {
 #if 0
   // TODO(rtenneti): Should we enable this code in chromium?
@@ skipping 1756 matching lines @@
   // If we changed the generator's batch state, restore original batch state.
   if (!already_in_batch_mode_) {
     DVLOG(1) << "Leaving Batch Mode.";
     connection_->packet_generator_.FinishBatchOperations();
   }
   DCHECK_EQ(already_in_batch_mode_,
             connection_->packet_generator_.InBatchMode());
 }
 
 }  // namespace net