Fix a newly introduced bug in QUIC's PacingSender where burst_tokens_

net/quic/congestion_control/pacing_sender.cc

 // Copyright (c) 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/congestion_control/pacing_sender.h"
 
 namespace net {
 
 PacingSender::PacingSender(SendAlgorithmInterface* sender,
                            QuicTime::Delta alarm_granularity,
@@ skipping 23 matching lines @@
       feedback, feedback_receive_time);
 }
 
 void PacingSender::OnCongestionEvent(bool rtt_updated,
                                      QuicByteCount bytes_in_flight,
                                      const CongestionMap& acked_packets,
                                      const CongestionMap& lost_packets) {
   if (rtt_updated) {
     has_valid_rtt_ = true;
   }
-  if (bytes_in_flight == 0) {
-    // Add more burst tokens anytime the connection is entering quiescence.
-    burst_tokens_ = initial_packet_burst_;
-  }
   sender_->OnCongestionEvent(
       rtt_updated, bytes_in_flight, acked_packets, lost_packets);
 }
 
 bool PacingSender::OnPacketSent(
     QuicTime sent_time,
     QuicByteCount bytes_in_flight,
     QuicPacketSequenceNumber sequence_number,
     QuicByteCount bytes,
     HasRetransmittableData has_retransmittable_data) {
@@ skipping 56 matching lines @@
 QuicTime::Delta PacingSender::TimeUntilSend(
       QuicTime now,
       QuicByteCount bytes_in_flight,
       HasRetransmittableData has_retransmittable_data) const {
   QuicTime::Delta time_until_send =
       sender_->TimeUntilSend(now, bytes_in_flight, has_retransmittable_data);
   if (!has_valid_rtt_) {
     // Don't pace if we don't have an updated RTT estimate.
     return time_until_send;
   }
+  if (bytes_in_flight == 0) {
+    // Add more burst tokens anytime the connection is entering quiescence.
+    burst_tokens_ = initial_packet_burst_;
+  }
   if (burst_tokens_ > 0) {
     // Don't pace if we have burst tokens available.
     return time_until_send;
   }
 
   if (!time_until_send.IsZero()) {
     DCHECK(time_until_send.IsInfinite());
     // The underlying sender prevents sending.
     return time_until_send;
   }
@@ skipping 26 matching lines @@
 
 QuicTime::Delta PacingSender::RetransmissionDelay() const {
   return sender_->RetransmissionDelay();
 }
 
 QuicByteCount PacingSender::GetCongestionWindow() const {
   return sender_->GetCongestionWindow();
 }
 
 }  // namespace net