Attach QuicAckNotifiers to the serialized packet, instead of individual

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 449 matching lines @@
   QuicPacketSequenceNumber newest_transmission =
       transmission_info.all_transmissions == nullptr
           ? sequence_number
           : *transmission_info.all_transmissions->rbegin();
   // This packet has been revived at the receiver. If we were going to
   // retransmit it, do not retransmit it anymore.
   pending_retransmissions_.erase(newest_transmission);
 
   // The AckNotifierManager needs to be notified for revived packets,
   // since it indicates the packet arrived from the appliction's perspective.
-  if (transmission_info.retransmittable_frames) {
-    ack_notifier_manager_.OnPacketAcked(
-        newest_transmission, delta_largest_observed);
+  if (FLAGS_quic_attach_ack_notifiers_to_packets ||
+      transmission_info.retransmittable_frames) {
+    ack_notifier_manager_.OnPacketAcked(newest_transmission,
+                                        delta_largest_observed);
   }
 
   unacked_packets_.RemoveRetransmittability(sequence_number);
 }
 
 void QuicSentPacketManager::MarkPacketHandled(
     QuicPacketSequenceNumber sequence_number,
     const TransmissionInfo& info,
     QuicTime::Delta delta_largest_observed) {
   QuicPacketSequenceNumber newest_transmission =
@@ skipping 470 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