gfe-relnote: (n/a) Deprecate --gfe2_reloadable_flag_quic_bbr2_always_count_loss_events.

PiperOrigin-RevId: 298356007
Change-Id: I5208f2d6f74956e6a2863931f4f1ded5c0ee27a3

quic/core/congestion_control/bbr2_misc.h

diff --git a/quic/core/congestion_control/bbr2_misc.h b/quic/core/congestion_control/bbr2_misc.h
index dd71520..d38ad5a 100644
--- a/quic/core/congestion_control/bbr2_misc.h
+++ b/quic/core/congestion_control/bbr2_misc.h
@@ -380,8 +380,6 @@
 
   int64_t loss_events_in_round() const { return loss_events_in_round_; }
 
-  bool always_count_loss_events() const { return always_count_loss_events_; }
-
   QuicPacketNumber end_of_app_limited_phase() const {
     return bandwidth_sampler_.end_of_app_limited_phase();
   }
@@ -437,9 +435,6 @@
   QuicByteCount bytes_lost_in_round_ = 0;
   // Number of loss marking events in the current round.
   int64_t loss_events_in_round_ = 0;
-  // Latched value of --quic_bbr2_always_count_loss_events.
-  const bool always_count_loss_events_ =
-      GetQuicReloadableFlag(quic_bbr2_always_count_loss_events);
 
   // Max bandwidth in the current round. Updated once per congestion event.
   QuicBandwidth bandwidth_latest_ = QuicBandwidth::Zero();

quic/core/congestion_control/bbr2_probe_bw.cc

diff --git a/quic/core/congestion_control/bbr2_probe_bw.cc b/quic/core/congestion_control/bbr2_probe_bw.cc
index dc89e8f..b6aedbf 100644
--- a/quic/core/congestion_control/bbr2_probe_bw.cc
+++ b/quic/core/congestion_control/bbr2_probe_bw.cc
@@ -156,12 +156,8 @@
     return NOT_ADAPTED_INVALID_SAMPLE;
   }
 
-  bool has_enough_loss_events = true;
-  if (model_->always_count_loss_events()) {
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr2_always_count_loss_events, 2, 2);
-    has_enough_loss_events =
-        model_->loss_events_in_round() >= Params().probe_bw_full_loss_count;
-  }
+  const bool has_enough_loss_events =
+      model_->loss_events_in_round() >= Params().probe_bw_full_loss_count;
 
   if (has_enough_loss_events && model_->IsInflightTooHigh(congestion_event)) {
     if (cycle_.is_sample_from_probing) {

quic/core/congestion_control/bbr2_startup.cc

diff --git a/quic/core/congestion_control/bbr2_startup.cc b/quic/core/congestion_control/bbr2_startup.cc
index c87f715..6ffea8e 100644
--- a/quic/core/congestion_control/bbr2_startup.cc
+++ b/quic/core/congestion_control/bbr2_startup.cc
@@ -18,8 +18,7 @@
     : Bbr2ModeBase(sender, model),
       full_bandwidth_reached_(false),
       full_bandwidth_baseline_(QuicBandwidth::Zero()),
-      rounds_without_bandwidth_growth_(0),
-      loss_events_in_round_(0) {
+      rounds_without_bandwidth_growth_(0) {
   // Clear some startup stats if |sender_->connection_stats_| has been used by
   // another sender, which happens e.g. when QuicConnection switch send
   // algorithms.
@@ -41,11 +40,11 @@
     QuicByteCount /*prior_in_flight*/,
     QuicTime /*event_time*/,
     const AckedPacketVector& /*acked_packets*/,
-    const LostPacketVector& lost_packets,
+    const LostPacketVector& /*lost_packets*/,
     const Bbr2CongestionEvent& congestion_event) {
   CheckFullBandwidthReached(congestion_event);
 
-  CheckExcessiveLosses(lost_packets, congestion_event);
+  CheckExcessiveLosses(congestion_event);
 
   model_->set_pacing_gain(Params().startup_gain);
   model_->set_cwnd_gain(Params().startup_gain);
@@ -88,24 +87,12 @@
 }
 
 void Bbr2StartupMode::CheckExcessiveLosses(
-    const LostPacketVector& lost_packets,
     const Bbr2CongestionEvent& congestion_event) {
   if (full_bandwidth_reached_) {
     return;
   }
 
-  if (!lost_packets.empty()) {
-    ++loss_events_in_round_;
-  }
-
-  if (model_->always_count_loss_events()) {
-    DCHECK_EQ(loss_events_in_round_, model_->loss_events_in_round());
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr2_always_count_loss_events, 1, 2);
-  }
-
-  const int64_t loss_events_in_round = model_->always_count_loss_events()
-                                           ? model_->loss_events_in_round()
-                                           : loss_events_in_round_;
+  const int64_t loss_events_in_round = model_->loss_events_in_round();
 
   // TODO(wub): In TCP, loss based exit only happens at end of a loss round, in
   // QUIC we use the end of the normal round here. It is possible to exit after
@@ -132,8 +119,6 @@
     full_bandwidth_reached_ = true;
     sender_->connection_stats_->bbr_exit_startup_due_to_loss = true;
   }
-
-  loss_events_in_round_ = 0;
 }
 
 Bbr2StartupMode::DebugState Bbr2StartupMode::ExportDebugState() const {

quic/core/congestion_control/bbr2_startup.h

diff --git a/quic/core/congestion_control/bbr2_startup.h b/quic/core/congestion_control/bbr2_startup.h
index 6477957..aae34c0 100644
--- a/quic/core/congestion_control/bbr2_startup.h
+++ b/quic/core/congestion_control/bbr2_startup.h
@@ -51,16 +51,11 @@
 
   void CheckFullBandwidthReached(const Bbr2CongestionEvent& congestion_event);
 
-  void CheckExcessiveLosses(const LostPacketVector& lost_packets,
-                            const Bbr2CongestionEvent& congestion_event);
+  void CheckExcessiveLosses(const Bbr2CongestionEvent& congestion_event);
 
   bool full_bandwidth_reached_;
   QuicBandwidth full_bandwidth_baseline_;
   QuicRoundTripCount rounds_without_bandwidth_growth_;
-
-  // Number of loss events in the current round trip.
-  // TODO(wub): Remove when deprecating --quic_bbr2_always_count_loss_events.
-  int64_t loss_events_in_round_;
 };
 
 QUIC_EXPORT_PRIVATE std::ostream& operator<<(