Deprecate FLAGS_quic_simplify_loss_detection.

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index 9d4f694376a6bcf0c0903ab264a54e2863bf603c..28c32c05da251bb5683be25399d20cac6ae1c157 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -320,21 +320,7 @@ void QuicSentPacketManager::HandleAckForSentPackets(
 
     if ((ack_frame.missing && ack_frame.packets.Contains(packet_number)) ||
         (!ack_frame.missing && !ack_frame.packets.Contains(packet_number))) {
-      // Don't continue to increase the nack count for packets not in flight.
-      if (FLAGS_quic_simplify_loss_detection || !it->in_flight) {
-        continue;
-      }
-      // Consider it multiple nacks when there is a gap between the missing
-      // packet and the largest observed, since the purpose of a nack
-      // threshold is to tolerate re-ordering.  This handles both StretchAcks
-      // and Forward Acks.
-      // The nack count only increases when the largest observed increases.
-      QuicPacketCount min_nacks = ack_frame.largest_observed - packet_number;
-      // Truncated acks can nack the largest observed, so use a min of 1.
-      if (min_nacks == 0) {
-        min_nacks = 1;
-      }
-      unacked_packets_.NackPacket(packet_number, min_nacks);
+      // Packet is still missing.
       continue;
     }
     // Packet was acked, so remove it from our unacked packet list.