Deprecate quic_bbr2_simplify_inflight_hi.

PiperOrigin-RevId: 852619967

quiche/common/quiche_feature_flags_list.h

diff --git a/quiche/common/quiche_feature_flags_list.h b/quiche/common/quiche_feature_flags_list.h
index 35d4b14..4136886 100755
--- a/quiche/common/quiche_feature_flags_list.h
+++ b/quiche/common/quiche_feature_flags_list.h
@@ -15,7 +15,6 @@
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bandwidth_sampler_guard_rtt_subtraction, false, false, "When true, BandwidthSampler::OnPacketAcknowledgedInner() will return early rather than compute a negative RTT.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_extra_acked_window, false, true, "When true, the BBR4 copt sets the extra_acked window to 20 RTTs and BBR5 sets it to 40 RTTs.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_probe_two_rounds, true, true, "When true, the BB2U copt causes BBR2 to wait two rounds with out draining the queue before exiting PROBE_UP and BB2S has the same effect in STARTUP.")
-QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_simplify_inflight_hi, true, true, "When true, the BBHI copt causes QUIC BBRv2 to use a simpler algorithm for raising inflight_hi in PROBE_UP.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr_always_exit_startup_on_loss, false, false, "Lets BBRv1 exit STARTUP if a large number of packets was lost even if there is no non-app-limited samples. Similar to applying connection option B1AL to all connection.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr_exit_startup_on_loss, false, false, "Enables negotiation of a connection option (B1AL) that lets BBRv1 exit STARTUP if a large number of packets was lost even if there is no non-app-limited sample.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_block_until_settings_received_copt, true, true, "If enabled and a BSUS connection is received, blocks server connections until SETTINGS frame is received.")

quiche/quic/core/congestion_control/bbr2_sender.cc

diff --git a/quiche/quic/core/congestion_control/bbr2_sender.cc b/quiche/quic/core/congestion_control/bbr2_sender.cc
index 21134ac..bfb2032 100644
--- a/quiche/quic/core/congestion_control/bbr2_sender.cc
+++ b/quiche/quic/core/congestion_control/bbr2_sender.cc
@@ -200,9 +200,7 @@
   if (ContainsQuicTag(connection_options, kB206)) {
     params_.startup_full_loss_count = params_.probe_bw_full_loss_count;
   }
-  if (GetQuicReloadableFlag(quic_bbr2_simplify_inflight_hi) &&
-      ContainsQuicTag(connection_options, kBBHI)) {
-    QUIC_RELOADABLE_FLAG_COUNT(quic_bbr2_simplify_inflight_hi);
+  if (ContainsQuicTag(connection_options, kBBHI)) {
     params_.probe_up_simplify_inflight_hi = true;
     // Simplify inflight_hi is intended as an alternative to ignoring it,
     // so ensure we're not ignoring it.

quiche/quic/core/congestion_control/bbr2_simulator_test.cc

diff --git a/quiche/quic/core/congestion_control/bbr2_simulator_test.cc b/quiche/quic/core/congestion_control/bbr2_simulator_test.cc
index 3cc8198..e79e160 100644
--- a/quiche/quic/core/congestion_control/bbr2_simulator_test.cc
+++ b/quiche/quic/core/congestion_control/bbr2_simulator_test.cc
@@ -1028,7 +1028,6 @@
 
 // Test Bbr2's reaction to a 100x bandwidth increase during a transfer with BBHI
 TEST_F(Bbr2DefaultTopologyTest, QUIC_SLOW_TEST(BandwidthIncreaseBBHI)) {
-  SetQuicReloadableFlag(quic_bbr2_simplify_inflight_hi, true);
   SetConnectionOption(kBBHI);
   DefaultTopologyParams params;
   params.local_link.bandwidth = QuicBandwidth::FromKBitsPerSecond(15000);
@@ -1062,7 +1061,6 @@
 // in the presence of ACK aggregation.
 TEST_F(Bbr2DefaultTopologyTest,
        QUIC_SLOW_TEST(BandwidthIncreaseBBHIAggregation)) {
-  SetQuicReloadableFlag(quic_bbr2_simplify_inflight_hi, true);
   SetConnectionOption(kBBHI);
   DefaultTopologyParams params;
   params.local_link.bandwidth = QuicBandwidth::FromKBitsPerSecond(15000);
@@ -1103,7 +1101,6 @@
 // min_bytes_in_flight_in_round, in the presence of ACK aggregation.
 TEST_F(Bbr2DefaultTopologyTest,
        QUIC_SLOW_TEST(BandwidthIncreaseBBHI_B202Aggregation)) {
-  SetQuicReloadableFlag(quic_bbr2_simplify_inflight_hi, true);
   SetConnectionOption(kBBHI);
   SetConnectionOption(kB202);
   DefaultTopologyParams params;
@@ -1361,7 +1358,6 @@
        QUIC_SLOW_TEST(BandwidthIncreaseBB2UandBBHIAggregation)) {
   SetQuicReloadableFlag(quic_bbr2_probe_two_rounds, true);
   SetConnectionOption(kBB2U);
-  SetQuicReloadableFlag(quic_bbr2_simplify_inflight_hi, true);
   SetConnectionOption(kBBHI);
   DefaultTopologyParams params;
   params.local_link.bandwidth = QuicBandwidth::FromKBitsPerSecond(15000);