Deprecate --gfe2_reloadable_flag_quic_bbr2_support_max_bootstrap_cwnd.

PiperOrigin-RevId: 344823608
Change-Id: I001a91418e5ca3fb07ad8bd2edf8fed791e6255f

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 e0bd610..9a9cda0 100644
--- a/quic/core/congestion_control/bbr2_sender.cc
+++ b/quic/core/congestion_control/bbr2_sender.cc
@@ -121,9 +121,7 @@
   if (config.HasClientRequestedIndependentOption(kB2HR, perspective)) {
     params_.inflight_hi_headroom = 0.15;
   }
-  if (GetQuicReloadableFlag(quic_bbr2_support_max_bootstrap_cwnd) &&
-      config.HasClientRequestedIndependentOption(kICW1, perspective)) {
-    QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr2_support_max_bootstrap_cwnd, 1, 4);
+  if (config.HasClientRequestedIndependentOption(kICW1, perspective)) {
     max_cwnd_when_network_parameters_adjusted_ = 100 * kDefaultTCPMSS;
   }
 
@@ -187,22 +185,14 @@
         std::max(params.bandwidth, model_.BandwidthEstimate());
     connection_stats_->cwnd_bootstrapping_rtt_us =
         model_.MinRtt().ToMicroseconds();
-    if (GetQuicReloadableFlag(quic_bbr2_support_max_bootstrap_cwnd)) {
-      if (params.max_initial_congestion_window > 0) {
-        QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr2_support_max_bootstrap_cwnd, 2,
-                                     4);
-        max_cwnd_when_network_parameters_adjusted_ =
-            params.max_initial_congestion_window * kDefaultTCPMSS;
-      } else {
-        QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr2_support_max_bootstrap_cwnd, 3,
-                                     4);
-      }
-      cwnd_ = cwnd_limits().ApplyLimits(
-          std::min(max_cwnd_when_network_parameters_adjusted_,
-                   model_.BDP(effective_bandwidth)));
-    } else {
-      cwnd_ = cwnd_limits().ApplyLimits(model_.BDP(effective_bandwidth));
+
+    if (params.max_initial_congestion_window > 0) {
+      max_cwnd_when_network_parameters_adjusted_ =
+          params.max_initial_congestion_window * kDefaultTCPMSS;
     }
+    cwnd_ = cwnd_limits().ApplyLimits(
+        std::min(max_cwnd_when_network_parameters_adjusted_,
+                 model_.BDP(effective_bandwidth)));
 
     if (!params.allow_cwnd_to_decrease) {
       cwnd_ = std::max(cwnd_, prior_cwnd);

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 c3362b3..d372cf9 100644
--- a/quic/core/congestion_control/bbr2_simulator_test.cc
+++ b/quic/core/congestion_control/bbr2_simulator_test.cc
@@ -1105,12 +1105,10 @@
       SendAlgorithmInterface::NetworkParams(1024 * params.BottleneckBandwidth(),
                                             QuicTime::Delta::Zero(), false));
 
-  if (GetQuicReloadableFlag(quic_bbr2_support_max_bootstrap_cwnd)) {
-    // Verify cwnd is capped at 200.
-    EXPECT_EQ(200 * kDefaultTCPMSS,
-              sender_->ExportDebugState().congestion_window);
-    EXPECT_GT(1024 * params.BottleneckBandwidth(), sender_->PacingRate(0));
-  }
+  // Verify cwnd is capped at 200.
+  EXPECT_EQ(200 * kDefaultTCPMSS,
+            sender_->ExportDebugState().congestion_window);
+  EXPECT_GT(1024 * params.BottleneckBandwidth(), sender_->PacingRate(0));
 }
 
 TEST_F(Bbr2DefaultTopologyTest,
@@ -1132,12 +1130,10 @@
   network_params.max_initial_congestion_window = 100;
   sender_connection()->AdjustNetworkParameters(network_params);
 
-  if (GetQuicReloadableFlag(quic_bbr2_support_max_bootstrap_cwnd)) {
-    // Verify cwnd is capped at 100.
-    EXPECT_EQ(100 * kDefaultTCPMSS,
-              sender_->ExportDebugState().congestion_window);
-    EXPECT_GT(1024 * params.BottleneckBandwidth(), sender_->PacingRate(0));
-  }
+  // Verify cwnd is capped at 100.
+  EXPECT_EQ(100 * kDefaultTCPMSS,
+            sender_->ExportDebugState().congestion_window);
+  EXPECT_GT(1024 * params.BottleneckBandwidth(), sender_->PacingRate(0));
 }
 
 TEST_F(Bbr2DefaultTopologyTest,
@@ -1159,12 +1155,10 @@
       SendAlgorithmInterface::NetworkParams(1024 * params.BottleneckBandwidth(),
                                             QuicTime::Delta::Zero(), false));
 
-  if (GetQuicReloadableFlag(quic_bbr2_support_max_bootstrap_cwnd)) {
-    // Verify cwnd is capped at 100.
-    EXPECT_EQ(100 * kDefaultTCPMSS,
-              sender_->ExportDebugState().congestion_window);
-    EXPECT_GT(1024 * params.BottleneckBandwidth(), sender_->PacingRate(0));
-  }
+  // Verify cwnd is capped at 100.
+  EXPECT_EQ(100 * kDefaultTCPMSS,
+            sender_->ExportDebugState().congestion_window);
+  EXPECT_GT(1024 * params.BottleneckBandwidth(), sender_->PacingRate(0));
 }
 
 // All Bbr2MultiSenderTests uses the following network topology:

quic/core/quic_flags_list.h

diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index a193d50..01062fd 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -13,7 +13,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_avoid_too_low_probe_bw_cwnd, false)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_fewer_startup_round_trips, false)
 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_bytes_delivered, false)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_can_send_ack_frequency, true)
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_conservative_bursts, false)