Fix a bug where packet received times aren't sent if the approximate now

net/quic/quic_received_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_received_packet_manager.h"
 
 #include <limits>
 #include <utility>
 
 #include "base/logging.h"
@@ skipping 211 matching lines @@
     QuicAckFrame* ack_frame, QuicTime approximate_now) {
   *ack_frame = ack_frame_;
   ack_frame->entropy_hash = EntropyHash(ack_frame_.largest_observed);
 
   if (time_largest_observed_ == QuicTime::Zero()) {
     // We have received no packets.
     ack_frame->delta_time_largest_observed = QuicTime::Delta::Infinite();
     return;
   }
 
-  if (approximate_now < time_largest_observed_) {
-    // Approximate now may well be "in the past".
-    ack_frame->delta_time_largest_observed = QuicTime::Delta::Zero();
-    return;
-  }
-
+  // Ensure the delta is zero if approximate now is "in the past".
   ack_frame->delta_time_largest_observed =
-      approximate_now.Subtract(time_largest_observed_);
+      approximate_now < time_largest_observed_ ?
+          QuicTime::Delta::Zero() :
+          approximate_now.Subtract(time_largest_observed_);
 
   // Remove all packets that are too far from largest_observed to express.
   received_packet_times_.remove_if(isTooLarge(ack_frame_.largest_observed));
 
   ack_frame->received_packet_times = received_packet_times_;
   received_packet_times_.clear();
 }
 
 bool QuicReceivedPacketManager::GenerateCongestionFeedback(
     QuicCongestionFeedbackFrame* feedback) {
@@ skipping 37 matching lines @@
              peer_least_packet_awaiting_ack_);
 }
 
 bool QuicReceivedPacketManager::HasNewMissingPackets() {
   return !ack_frame_.missing_packets.empty() &&
       (ack_frame_.largest_observed -
        *ack_frame_.missing_packets.rbegin()) <= kMaxPacketsAfterNewMissing;
 }
 
 }  // namespace net