Deprecate --gfe2_reloadable_flag_quic_bbr2_check_cwnd_limited_before_aggregation_epoch.

PiperOrigin-RevId: 410059367

quic/core/congestion_control/bbr2_sender.cc

diff --git a/quic/core/congestion_control/bbr2_sender.cc b/quic/core/congestion_control/bbr2_sender.cc
index 3f1c449..c8acb9e 100644
--- a/quic/core/congestion_control/bbr2_sender.cc
+++ b/quic/core/congestion_control/bbr2_sender.cc
@@ -168,11 +168,7 @@
   if (ContainsQuicTag(connection_options, kBBQ9)) {
     params_.bw_lo_mode_ = Bbr2Params::QuicBandwidthLoMode::CWND_REDUCTION;
   }
-  if (GetQuicReloadableFlag(
-          quic_bbr2_check_cwnd_limited_before_aggregation_epoch) &&
-      ContainsQuicTag(connection_options, kB201)) {
-    QUIC_RELOADABLE_FLAG_COUNT(
-        quic_bbr2_check_cwnd_limited_before_aggregation_epoch);
+  if (ContainsQuicTag(connection_options, kB201)) {
     params_.probe_bw_check_cwnd_limited_before_aggregation_epoch = true;
   }
   if (GetQuicReloadableFlag(quic_bbr2_no_probe_up_exit_if_no_queue) &&

quic/core/congestion_control/bbr2_simulator_test.cc

diff --git a/quic/core/congestion_control/bbr2_simulator_test.cc b/quic/core/congestion_control/bbr2_simulator_test.cc
index 1ad799b..8ac2049 100644
--- a/quic/core/congestion_control/bbr2_simulator_test.cc
+++ b/quic/core/congestion_control/bbr2_simulator_test.cc
@@ -508,8 +508,6 @@
 }
 
 TEST_F(Bbr2DefaultTopologyTest, SimpleTransferB201) {
-  SetQuicReloadableFlag(quic_bbr2_check_cwnd_limited_before_aggregation_epoch,
-                        true);
   SetConnectionOption(kB201);
   DefaultTopologyParams params;
   CreateNetwork(params);
@@ -681,8 +679,6 @@
 }
 
 TEST_F(Bbr2DefaultTopologyTest, SimpleTransfer2RTTAggregationBytesB201) {
-  SetQuicReloadableFlag(quic_bbr2_check_cwnd_limited_before_aggregation_epoch,
-                        true);
   SetConnectionOption(kB201);
   DefaultTopologyParams params;
   CreateNetwork(params);

quic/core/quic_flags_list.h

diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index e8aea24..996fddf 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -19,8 +19,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_donot_check_amplification_limit_with_pending_timer_credit, false)
 // If bytes in flight has dipped below 1.25*MaxBW in the last round, do not exit PROBE_UP due to excess queue buildup.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_no_probe_up_exit_if_no_queue, true)
-// If true and connection option B201 is used, check if cwnd limited before aggregation epoch, instead of ack event, in PROBE_UP phase.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_check_cwnd_limited_before_aggregation_epoch, true)
 // If true, 1) NEW_TOKENs sent from a IETF QUIC session will include the cached network parameters proto, 2) A min_rtt received from a validated token will be used to set the initial rtt, 3) Enable bandwidth resumption for IETF QUIC when connection options BWRE or BWMX exists.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_add_cached_network_parameters_to_address_token, false)
 // If true, QUIC will default enable MTU discovery at server, with a target of 1450 bytes.