deprecate FLAGS_quic_reloadable_flag_quic_bbr_keep_sending_at_recent_rate in disabled state.

net/quic/core/quic_flags_list.h

 // 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.
 
 // This file intentionally does not have header guards, it's included
 // inside a macro to generate values.
 
 // This file contains the list of QUIC protocol flags.
 
 // If true, QUIC BBR congestion control may be enabled via Finch and/or via QUIC
@@ skipping 168 matching lines @@
 // If true, on server side, 8-byte connection ID in public header is read and
 // written in big endian.
 QUIC_FLAG(bool,
           FLAGS_quic_restart_flag_quic_big_endian_connection_id_server,
           false)
 
 // Simplify QUIC\'s adaptive time loss detection to measure the necessary
 // reordering window for every spurious retransmit.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_fix_adaptive_time_loss, false)
 
-// In QUIC BBR, keep sending at the max bandwidth observed in the previous 2
-// RTTs for another SRTT.
-QUIC_FLAG(bool,
-          FLAGS_quic_reloadable_flag_quic_bbr_keep_sending_at_recent_rate,
-          false)
-
 // Base CWND on SRTT instead of min_rtt for QUIC BBR.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_bbr_base_cwnd_on_srtt, false)
 
 // If true, enable random padding of size [1, 256] when response body is
 // compressed for QUIC version >= 38.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_enable_random_padding, false)
 
 // Use conservation in PROBE_BW ouside of super-unity gain and immediately
 // preceeding cycle.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_bbr_extra_conservation, false)
@@ skipping 14 matching lines @@
           false)
 
 // Fix the algorithm used by packet conservation.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_bbr_fix_conservation, false)
 
 // If enabled, use refactored stream creation methods.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_refactor_stream_creation, false)
 
 // A second take on fixing QUIC BBR packet conservation.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_bbr_fix_conservation2, false)