Deprecate --gfe2_reloadable_flag_quic_bbr2_use_tcp_inflight_hi_headroom.

PiperOrigin-RevId: 343849729
Change-Id: I07f7c5e7c5f117319f793b552f9cf47171be74eb

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 c3abffe..6b93074 100644
--- a/quic/core/congestion_control/bbr2_sender.cc
+++ b/quic/core/congestion_control/bbr2_sender.cc
@@ -123,9 +123,7 @@
   if (config.HasClientRequestedIndependentOption(kB2LO, perspective)) {
     params_.ignore_inflight_lo = true;
   }
-  if (GetQuicReloadableFlag(quic_bbr2_use_tcp_inflight_hi_headroom) &&
-      config.HasClientRequestedIndependentOption(kB2HR, perspective)) {
-    QUIC_RELOADABLE_FLAG_COUNT(quic_bbr2_use_tcp_inflight_hi_headroom);
+  if (config.HasClientRequestedIndependentOption(kB2HR, perspective)) {
     params_.inflight_hi_headroom = 0.15;
   }
   if (GetQuicReloadableFlag(quic_bbr2_support_max_bootstrap_cwnd) &&

quic/core/quic_flags_list.h

diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 7ead17a..4c5e947 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -17,7 +17,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_startup_loss_exit_use_max_delivered, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_support_max_bootstrap_cwnd, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_use_post_inflight_to_detect_queuing, true)
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_use_tcp_inflight_hi_headroom, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_can_send_ack_frequency, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_check_keys_before_writing, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_clean_up_spdy_session_destructor, true)