Deprecate quic_simple_packet_number_length_2.

net/quic/core/quic_connection.cc

Index: net/quic/core/quic_connection.cc
diff --git a/net/quic/core/quic_connection.cc b/net/quic/core/quic_connection.cc
index 5793b15c890fc76a99d8563d77a2a59664f47fe1..1cacb4956c2ef15286e33e12662e036c8368cedc 100644
--- a/net/quic/core/quic_connection.cc
+++ b/net/quic/core/quic_connection.cc
@@ -1691,15 +1691,6 @@ bool QuicConnection::WritePacket(SerializedPacket* packet) {
   DVLOG(1) << ENDPOINT << "time we began writing last sent packet: "
            << packet_send_time.ToDebuggingValue();
 
-  if (!FLAGS_quic_simple_packet_number_length_2) {
-    // TODO(ianswett): Change the packet number length and other packet creator
-    // options by a more explicit API than setting a struct value directly,
-    // perhaps via the NetworkChangeVisitor.
-    packet_generator_.UpdateSequenceNumberLength(
-        sent_packet_manager_->GetLeastUnacked(packet->path_id),
-        sent_packet_manager_->EstimateMaxPacketsInFlight(max_packet_length()));
-  }
-
   bool reset_retransmission_alarm = sent_packet_manager_->OnPacketSent(
       packet, packet->original_path_id, packet->original_packet_number,
       packet_send_time, packet->transmission_type, IsRetransmittable(*packet));
@@ -1708,13 +1699,11 @@ bool QuicConnection::WritePacket(SerializedPacket* packet) {
     SetRetransmissionAlarm();
   }
 
-  if (FLAGS_quic_simple_packet_number_length_2) {
-    // The packet number length must be updated after OnPacketSent, because it
-    // may change the packet number length in packet.
-    packet_generator_.UpdateSequenceNumberLength(
-        sent_packet_manager_->GetLeastUnacked(packet->path_id),
-        sent_packet_manager_->EstimateMaxPacketsInFlight(max_packet_length()));
-  }
+  // The packet number length must be updated after OnPacketSent, because it
+  // may change the packet number length in packet.
+  packet_generator_.UpdateSequenceNumberLength(
+      sent_packet_manager_->GetLeastUnacked(packet->path_id),
+      sent_packet_manager_->EstimateMaxPacketsInFlight(max_packet_length()));
 
   stats_.bytes_sent += result.bytes_written;
   ++stats_.packets_sent;