Deprecate --gfe2_reloadable_flag_quic_bbr_fix_pacing_rate.

PiperOrigin-RevId: 320965724
Change-Id: I896e76a20017bb18aac166f2800e23813faaba76

quic/core/congestion_control/bbr_sender_test.cc

diff --git a/quic/core/congestion_control/bbr_sender_test.cc b/quic/core/congestion_control/bbr_sender_test.cc
index 8855918..c947568 100644
--- a/quic/core/congestion_control/bbr_sender_test.cc
+++ b/quic/core/congestion_control/bbr_sender_test.cc
@@ -116,7 +116,6 @@
 
   void SetUp() override {
     SetQuicReloadableFlag(quic_fix_bbr_cwnd_in_bandwidth_resumption, true);
-    SetQuicReloadableFlag(quic_bbr_fix_pacing_rate, true);
     SetQuicReloadableFlag(quic_bbr_donot_inject_bandwidth, true);
     if (GetQuicFlag(FLAGS_quic_bbr_test_regression_mode) == "regress") {
       SendAlgorithmTestResult expected;
@@ -1056,9 +1055,9 @@
   }
   EXPECT_EQ(kTestLinkBandwidth * kTestRtt,
             sender_->ExportDebugState().congestion_window);
-  if (GetQuicReloadableFlag(quic_bbr_fix_pacing_rate)) {
-    EXPECT_EQ(kTestLinkBandwidth, sender_->PacingRate(/*bytes_in_flight=*/0));
-  }
+
+  EXPECT_EQ(kTestLinkBandwidth, sender_->PacingRate(/*bytes_in_flight=*/0));
+
   EXPECT_APPROX_EQ(kTestRtt, sender_->ExportDebugState().min_rtt, 0.01f);
 
   DriveOutOfStartup();
@@ -1140,19 +1139,11 @@
   }
   EXPECT_LT(previous_cwnd, sender_->ExportDebugState().congestion_window);
 
-  if (GetQuicReloadableFlag(quic_bbr_fix_pacing_rate)) {
-    // Verify pacing rate is re-calculated based on the new cwnd and min_rtt.
-    EXPECT_APPROX_EQ(QuicBandwidth::FromBytesAndTimeDelta(
-                         sender_->ExportDebugState().congestion_window,
-                         sender_->ExportDebugState().min_rtt),
-                     sender_->PacingRate(/*bytes_in_flight=*/0), 0.01f);
-  } else {
-    // Pacing rate is still based on initial cwnd.
-    EXPECT_APPROX_EQ(QuicBandwidth::FromBytesAndTimeDelta(
-                         kInitialCongestionWindowPackets * kDefaultTCPMSS,
-                         sender_->ExportDebugState().min_rtt),
-                     sender_->PacingRate(/*bytes_in_flight=*/0), 0.01f);
-  }
+  // Verify pacing rate is re-calculated based on the new cwnd and min_rtt.
+  EXPECT_APPROX_EQ(QuicBandwidth::FromBytesAndTimeDelta(
+                       sender_->ExportDebugState().congestion_window,
+                       sender_->ExportDebugState().min_rtt),
+                   sender_->PacingRate(/*bytes_in_flight=*/0), 0.01f);
 }
 
 TEST_F(BbrSenderTest, RecalculatePacingRateOnCwndChange0RTT) {
@@ -1173,21 +1164,12 @@
   // No Rtt sample is available.
   EXPECT_TRUE(sender_->ExportDebugState().min_rtt.IsZero());
 
-  if (GetQuicReloadableFlag(quic_bbr_fix_pacing_rate)) {
-    // Verify pacing rate is re-calculated based on the new cwnd and initial
-    // RTT.
-    EXPECT_APPROX_EQ(QuicBandwidth::FromBytesAndTimeDelta(
-                         sender_->ExportDebugState().congestion_window,
-                         rtt_stats_->initial_rtt()),
-                     sender_->PacingRate(/*bytes_in_flight=*/0), 0.01f);
-  } else {
-    // Pacing rate is still based on initial cwnd.
-    EXPECT_APPROX_EQ(
-        2.885f * QuicBandwidth::FromBytesAndTimeDelta(
-                     kInitialCongestionWindowPackets * kDefaultTCPMSS,
-                     rtt_stats_->initial_rtt()),
-        sender_->PacingRate(/*bytes_in_flight=*/0), 0.01f);
-  }
+  // Verify pacing rate is re-calculated based on the new cwnd and initial
+  // RTT.
+  EXPECT_APPROX_EQ(QuicBandwidth::FromBytesAndTimeDelta(
+                       sender_->ExportDebugState().congestion_window,
+                       rtt_stats_->initial_rtt()),
+                   sender_->PacingRate(/*bytes_in_flight=*/0), 0.01f);
 }
 
 TEST_F(BbrSenderTest, MitigateCwndBootstrappingOvershoot) {

quic/core/congestion_control/send_algorithm_interface.h

diff --git a/quic/core/congestion_control/send_algorithm_interface.h b/quic/core/congestion_control/send_algorithm_interface.h
index ea0c375..a8d2afa 100644
--- a/quic/core/congestion_control/send_algorithm_interface.h
+++ b/quic/core/congestion_control/send_algorithm_interface.h
@@ -44,8 +44,6 @@
           allow_cwnd_to_decrease(allow_cwnd_to_decrease),
           quic_fix_bbr_cwnd_in_bandwidth_resumption(
               GetQuicReloadableFlag(quic_fix_bbr_cwnd_in_bandwidth_resumption)),
-          quic_bbr_fix_pacing_rate(
-              GetQuicReloadableFlag(quic_bbr_fix_pacing_rate)),
           quic_bbr_donot_inject_bandwidth(
               GetQuicReloadableFlag(quic_bbr_donot_inject_bandwidth)) {}
 
@@ -66,7 +64,7 @@
     // TODO(b/131899599): Remove after impact of fix is measured.
     bool quic_fix_bbr_cwnd_in_bandwidth_resumption;
     // TODO(b/143540157): Remove after impact of fix is measured.
-    bool quic_bbr_fix_pacing_rate;
+    bool quic_bbr_fix_pacing_rate = true;
     // TODO(b/72089315, b/143891040): Remove after impact of fix is measured.
     bool quic_bbr_donot_inject_bandwidth;
   };