relnote: Use event_time instead of ApproximateNow() in QUIC cubic code. Protected by --quic_use_eve…

net/quic/core/congestion_control/cubic.cc

Index: net/quic/core/congestion_control/cubic.cc
diff --git a/net/quic/core/congestion_control/cubic.cc b/net/quic/core/congestion_control/cubic.cc
index f0a1871b70155b0f1a57325f25f5737be88fcbd5..0d6ff818df41b35cf0adf9c0dd548da8f7c9305e 100644
--- a/net/quic/core/congestion_control/cubic.cc
+++ b/net/quic/core/congestion_control/cubic.cc
@@ -106,10 +106,13 @@ QuicPacketCount Cubic::CongestionWindowAfterPacketLoss(
 
 QuicPacketCount Cubic::CongestionWindowAfterAck(
     QuicPacketCount current_congestion_window,
-    QuicTime::Delta delay_min) {
+    QuicTime::Delta delay_min,
+    QuicTime event_time) {
   acked_packets_count_ += 1;  // Packets acked.
   epoch_packets_count_ += 1;
-  QuicTime current_time = clock_->ApproximateNow();
+  QuicTime current_time = FLAGS_quic_use_event_time
+                              ? event_time
+                              : clock_->ApproximateNow();
 
   // Cubic is "independent" of RTT, the update is limited by the time elapsed.
   if (last_congestion_window_ == current_congestion_window &&