Deprecate quic_do_not_migrate_on_old_packet.

net/quic/core/quic_flags.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/quic_flags.h"
 
 // If true, it will return as soon as an error is detected while validating
 // CHLO.
 bool FLAGS_use_early_return_when_verifying_chlo = true;
 
@@ skipping 88 matching lines @@
 
 // If true, enables QUIC_VERSION_36.
 bool FLAGS_quic_enable_version_36 = true;
 
 // If true, requires support for X509 certificates in QUIC CHLO PDMDs.
 bool FLAGS_quic_require_x509 = true;
 
 // If true, deprecate safeguards for b/26023400.
 bool FLAGS_quic_deprecate_kfixd = false;
 
-// If true, a connection does not migrate on an old packet even the peer address
-// changes.
-bool FLAGS_quic_do_not_migrate_on_old_packet = true;
-
 // If true, use async codepaths to invoke ProofSource::GetProof.
 bool FLAGS_enable_async_get_proof = false;
 
 // If true, neuter null encrypted packets before sending the next handshake
 // message.
 bool FLAGS_quic_neuter_unencrypted_when_sending = false;
 
 // If true, QuicAlarm::Update will call a faster UpdateImpl implementation
 // instead of canceling and reregistering the alarm.
 bool FLAGS_quic_change_alarms_efficiently = false;
@@ skipping 24 matching lines @@
 // have been written and a FIN has been sent.
 bool FLAGS_quic_close_stream_after_writing_queued_data = false;
 
 // If true, close connection with QUIC_TOO_MANY_FRAME_GAPS error when number of
 // gaps in QuicStreamSequenceBuffer exceeds allowed limit.
 bool FLAGS_quic_limit_frame_gaps_in_buffer = false;
 
 // If true, QuicSentPacketManager will use inline pacing functionality instead
 // of wrapping the SendAlgorithm with a PacingSender.
 bool FLAGS_quic_use_inline_pacing = false;