Deprecate FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 in the disabled position because it neve…

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 142 matching lines @@
 
 // If true, multipath bit is not used in public flag.
 QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_remove_multipath_bit, false)
 
 // Allow QUIC's flow control autotuning to increase the window as
 // quickly for the first adjustment as in subsequent ones.
 QUIC_FLAG(bool,
           FLAGS_quic_reloadable_flag_quic_flow_control_faster_autotune,
           true)
 
-// Only consider using the ack spacing in QUIC BBR if 2 packets are acked at
-// once.
-QUIC_FLAG(bool, FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2, false)
-
 // If true, QUIC BBR stores a max filtered number of bytes delivered at a rate
 // faster than the sending rate.
 QUIC_FLAG(bool,
           FLAGS_quic_reloadable_flag_quic_bbr_ack_aggregation_bytes,
           false)
 
 // If true, allow cubic updates on every ack, rather than occasionally limiting
 // the frequency to once every 30ms.
 QUIC_FLAG(bool,
           FLAGS_quic_reloadable_flag_quic_enable_cubic_per_ack_updates,
@@ skipping 33 matching lines @@
 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)