Update from https://crrev.com/307330

net/quic/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/quic_sent_packet_manager.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 116 matching lines @@
     }
     send_algorithm_.reset(SendAlgorithmInterface::Create(
         clock_, &rtt_stats_, kBBR, stats_, initial_congestion_window_));
   }
   if (config.HasReceivedConnectionOptions() &&
       ContainsQuicTag(config.ReceivedConnectionOptions(), kRENO)) {
     send_algorithm_.reset(SendAlgorithmInterface::Create(
         clock_, &rtt_stats_, kReno, stats_, initial_congestion_window_));
   }
   if (HasClientSentConnectionOption(config, kPACE) ||
-      (FLAGS_quic_allow_bbr &&
-       HasClientSentConnectionOption(config, kTBBR))) {
+      FLAGS_quic_enable_pacing ||
+      (FLAGS_quic_allow_bbr && HasClientSentConnectionOption(config, kTBBR))) {
     EnablePacing();
   }
   if (HasClientSentConnectionOption(config, k1CON)) {
     send_algorithm_->SetNumEmulatedConnections(1);
   }
   if (HasClientSentConnectionOption(config, kNCON)) {
     n_connection_simulation_ = true;
   }
   if (HasClientSentConnectionOption(config, kNTLP)) {
     max_tail_loss_probes_ = 0;
@@ skipping 784 matching lines @@
   // Set up a pacing sender with a 1 millisecond alarm granularity, the same as
   // the default granularity of the Linux kernel's FQ qdisc.
   using_pacing_ = true;
   send_algorithm_.reset(
       new PacingSender(send_algorithm_.release(),
                        QuicTime::Delta::FromMilliseconds(1),
                        kInitialUnpacedBurst));
 }
 
 }  // namespace net