relnote: Deprecate FLAGS_quic_retransmit_via_onserializedpacket.

net/quic/quic_flags.cc

Index: net/quic/quic_flags.cc
diff --git a/net/quic/quic_flags.cc b/net/quic/quic_flags.cc
index 8b1f05e62db42e11f83ec01a9d2f77c6b816bc65..654891fd129d9cd5d0f03e5f1f1cbe76ee6e1ca1 100644
--- a/net/quic/quic_flags.cc
+++ b/net/quic/quic_flags.cc
@@ -139,10 +139,6 @@ bool FLAGS_quic_log_loss_event = true;
 // QuicPacketCreator.
 bool FLAGS_use_stream_frame_freelist = true;
 
-// Call QuicConnection::OnSerializedPacket instead of returning the
-// serialized packet when frames are retransmitted.
-bool FLAGS_quic_retransmit_via_onserializedpacket = true;
-
 // If true, for QUIC authenticated encryption algorithms, last 8 bytes
 // of IV comprise packet path id and lower 7 bytes of packet number.
 bool FLAGS_quic_include_path_id_in_iv = true;