Update from https://crrev.com/305340

net/quic/congestion_control/time_loss_algorithm.cc

 // Copyright 2014 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/time_loss_algorithm.h"
 
 #include "net/quic/congestion_control/rtt_stats.h"
 #include "net/quic/quic_protocol.h"
 
 namespace net {
@@ skipping 28 matching lines @@
       QuicTime::Delta::Max(rtt_stats.smoothed_rtt(), rtt_stats.latest_rtt())
           .Multiply(kLossDelayMultiplier));
 
   QuicPacketSequenceNumber sequence_number = unacked_packets.GetLeastUnacked();
   for (QuicUnackedPacketMap::const_iterator it = unacked_packets.begin();
        it != unacked_packets.end() && sequence_number <= largest_observed;
        ++it, ++sequence_number) {
     if (!it->in_flight) {
       continue;
     }
-    LOG_IF(DFATAL, it->nack_count == 0)
-        << "All packets less than largest observed should have been nacked.";
+    LOG_IF(DFATAL, it->nack_count == 0 && it->sent_time.IsInitialized())
+        << "All packets less than largest observed should have been nacked."
+        << "sequence_number:" << sequence_number
+        << " largest_observed:" << largest_observed;
 
     // Packets are sent in order, so break when we haven't waited long enough
     // to lose any more packets and leave the loss_time_ set for the timeout.
     QuicTime when_lost = it->sent_time.Add(loss_delay);
     if (time < when_lost) {
       loss_detection_timeout_ = when_lost;
       break;
     }
     lost_packets.insert(sequence_number);
   }
 
   return lost_packets;
 }
 
 // loss_time_ is updated in DetectLostPackets, which must be called every time
 // an ack is received or the timeout expires.
 QuicTime TimeLossAlgorithm::GetLossTimeout() const {
   return loss_detection_timeout_;
 }
 
 }  // namespace net