gfe-relnote: In QUIC, do not adjust burst token for bad bandwidth samples. Protected by gfe2_reloadable_flag_quic_conservative_bursts.

PiperOrigin-RevId: 249157565
Change-Id: Iedaf2a728f668c84ac18d71e06c63ee42bc761d3

quic/core/quic_sent_packet_manager.cc

diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index 202a8d8..527f820 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -275,7 +275,8 @@
     SetInitialRtt(rtt);
   }
   const QuicByteCount old_cwnd = send_algorithm_->GetCongestionWindow();
-  if (GetQuicReloadableFlag(quic_conservative_bursts) && using_pacing_) {
+  if (GetQuicReloadableFlag(quic_conservative_bursts) && using_pacing_ &&
+      !bandwidth.IsZero()) {
     QUIC_RELOADABLE_FLAG_COUNT(quic_conservative_bursts);
     pacing_sender_.SetBurstTokens(kConservativeUnpacedBurst);
   }