Minor change to QUIC's retransmission to not link old retransmissions

net/quic/quic_unacked_packet_map.cc

Index: net/quic/quic_unacked_packet_map.cc
diff --git a/net/quic/quic_unacked_packet_map.cc b/net/quic/quic_unacked_packet_map.cc
index 2f971ee5c302331dd7d5ed36206b509d4d931d6f..3bba773681cfb46f769f988a4f5912c55f72d2cb 100644
--- a/net/quic/quic_unacked_packet_map.cc
+++ b/net/quic/quic_unacked_packet_map.cc
@@ -95,16 +95,24 @@ void QuicUnackedPacketMap::OnRetransmittedPacket(
       old_info->all_transmissions = NULL;
     }
   }
-  if (transmission_info->all_transmissions == NULL) {
-    transmission_info->all_transmissions = new SequenceNumberList();
-    transmission_info->all_transmissions->push_back(old_sequence_number);
+  // Don't link old transmissions to new ones when version or
+  // encryption changes.
+  if (transmission_type == ALL_INITIAL_RETRANSMISSION ||
+      transmission_type == ALL_UNACKED_RETRANSMISSION) {
+    RemoveAckability(transmission_info);
+  } else {
+    if (transmission_info->all_transmissions == NULL) {
+      transmission_info->all_transmissions = new SequenceNumberList();
+      transmission_info->all_transmissions->push_back(old_sequence_number);
+    }
+    transmission_info->all_transmissions->push_back(new_sequence_number);
   }
-  transmission_info->all_transmissions->push_back(new_sequence_number);
   unacked_packets_.push_back(
       TransmissionInfo(frames,
                        transmission_info->sequence_number_length,
                        transmission_type,
                        transmission_info->all_transmissions));
+  RemoveObsoletePackets();
 }
 
 void QuicUnackedPacketMap::ClearAllPreviousRetransmissions() {
@@ -179,6 +187,23 @@ void QuicUnackedPacketMap::RemoveRetransmittability(
   delete all_transmissions;
 }
 
+void QuicUnackedPacketMap::RemoveAckability(TransmissionInfo* info) {
+  DCHECK(info->retransmittable_frames == NULL);
+  info->is_unackable = true;
+  SequenceNumberList* all_transmissions = info->all_transmissions;
+  if (all_transmissions == NULL) {
+    return;
+  }
+  for (SequenceNumberList::const_iterator it = all_transmissions->begin();
+       it != all_transmissions->end(); ++it) {
+    TransmissionInfo* transmission_info =
+        &unacked_packets_[*it - least_unacked_];
+    transmission_info->all_transmissions = NULL;
+    transmission_info->is_unackable = true;
+  }
+  delete all_transmissions;
+}
+
 void QuicUnackedPacketMap::MaybeRemoveRetransmittableFrames(
     TransmissionInfo* transmission_info) {
   if (transmission_info->retransmittable_frames != NULL) {
@@ -209,7 +234,8 @@ bool QuicUnackedPacketMap::IsPacketUseless(
 bool QuicUnackedPacketMap::IsPacketRemovable(
     QuicPacketSequenceNumber sequence_number,
     const TransmissionInfo& info) const {
-  return (sequence_number <= largest_observed_ ||
+  return (info.is_unackable ||
+          sequence_number <= largest_observed_ ||
           unacked_packets_.size() > kMaxTcpCongestionWindow) &&
       !info.in_flight &&
       info.retransmittable_frames == NULL &&