Deprecate FLAGS_quic_disable_pre_30. Remove QUIC versions [25-29].

net/quic/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/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 94 matching lines @@
 
 // If true, treat timestamps from SO_TIMESTAMPING as QuicWallTimes rather
 // than QuicTimes.
 bool FLAGS_quic_socket_walltimestamps = true;
 
 // If true, default to immediate forward secure once established on the
 // server side, and the IPFS connection option disables this instead of
 // enabling it.
 bool FLAGS_quic_default_immediate_forward_secure = true;
 
-// If true, disables support for QUIC version 29 and earlier.
-bool FLAGS_quic_disable_pre_30 = true;
-
 // If true, QUIC respect HTTP2 SETTINGS frame rather than always close the
 // connection.
 bool FLAGS_quic_respect_http2_settings_frame = true;
 
 // Do not use a QuicAckListener in order to confirm a larger Path MTU.
 bool FLAGS_quic_no_mtu_discovery_ack_listener = true;
 
 // Deprecate QuicPacketCreator::next_packet_number_length_ because it's no
 // longer necessary.
 bool FLAGS_quic_simple_packet_number_length = true;
@@ skipping 21 matching lines @@
 // 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;