No functional change. Minor change to reorder when the list of QuicAckListeners is swapped into th…

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 ab389ce631da89a0efb573da4a88f2bb9634b774..74813419ffe866806d751ec212bc8f226d20b958 100644
--- a/net/quic/quic_unacked_packet_map.cc
+++ b/net/quic/quic_unacked_packet_map.cc
@@ -51,13 +51,7 @@ void QuicUnackedPacketMap::AddSentPacket(SerializedPacket* packet,
   TransmissionInfo info(packet->retransmittable_frames,
                         packet->packet_number_length, transmission_type,
                         sent_time, bytes_sent, packet->is_fec_packet);
-  if (old_packet_number == 0) {
-    if (packet->retransmittable_frames != nullptr &&
-        packet->retransmittable_frames->HasCryptoHandshake() == IS_HANDSHAKE) {
-      ++pending_crypto_packet_count_;
-    }
-    info.ack_listeners.swap(packet->listeners);
-  } else {
+  if (old_packet_number > 0) {
     TransferRetransmissionInfo(old_packet_number, packet_number,
                                transmission_type, &info);
   }
@@ -68,6 +62,15 @@ void QuicUnackedPacketMap::AddSentPacket(SerializedPacket* packet,
     info.in_flight = true;
   }
   unacked_packets_.push_back(info);
+  // Swap the ack listeners after to avoid an extra list allocation.
+  // TODO(ianswett): Could use emplace_back when Chromium can.
+  if (old_packet_number == 0) {
+    if (packet->retransmittable_frames != nullptr &&
+        packet->retransmittable_frames->HasCryptoHandshake() == IS_HANDSHAKE) {
+      ++pending_crypto_packet_count_;
+    }
+    unacked_packets_.back().ack_listeners.swap(packet->listeners);
+  }
 }
 
 void QuicUnackedPacketMap::RemoveObsoletePackets() {