Replace the map in QuicAckNotifier with a counter.

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 558 matching lines @@
   } else {
     PendingRetransmissionMap::iterator it =
         pending_retransmissions_.find(original_sequence_number);
     if (it != pending_retransmissions_.end()) {
       pending_retransmissions_.erase(it);
     } else {
       DLOG(DFATAL) << "Expected sequence number to be in "
                    << "pending_retransmissions_.  sequence_number: "
                    << original_sequence_number;
     }
-    // A notifier may be waiting to hear about ACKs for the original sequence
-    // number. Inform them that the sequence number has changed.
-    ack_notifier_manager_.UpdateSequenceNumber(original_sequence_number,
-                                               sequence_number);
+    // Inform the ack notifier of retransmissions so it can calculate the
+    // retransmit rate.
+    ack_notifier_manager_.OnPacketRetransmitted(original_sequence_number,
+                                                sequence_number, bytes);
   }
 
   if (pending_timer_transmission_count_ > 0) {
     --pending_timer_transmission_count_;
   }
 
   if (unacked_packets_.bytes_in_flight() == 0) {
     // TODO(ianswett): Consider being less aggressive to force a new
     // recent_min_rtt, likely by not discarding a relatively new sample.
     DVLOG(1) << "Sampling a new recent min rtt within 2 samples. currently:"
@@ skipping 417 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