Change the QUIC CongestionMap to be based on a vector.

net/quic/congestion_control/pacing_sender.cc

Index: net/quic/congestion_control/pacing_sender.cc
diff --git a/net/quic/congestion_control/pacing_sender.cc b/net/quic/congestion_control/pacing_sender.cc
index cc4f983a809a55ebdc355e88faa96330b582dd27..002db987969c1cb2366caa46401450d824ac922d 100644
--- a/net/quic/congestion_control/pacing_sender.cc
+++ b/net/quic/congestion_control/pacing_sender.cc
@@ -36,8 +36,8 @@ void PacingSender::OnIncomingQuicCongestionFeedbackFrame(
 
 void PacingSender::OnCongestionEvent(bool rtt_updated,
                                      QuicByteCount bytes_in_flight,
-                                     const CongestionMap& acked_packets,
-                                     const CongestionMap& lost_packets) {
+                                     const CongestionVector& acked_packets,
+                                     const CongestionVector& lost_packets) {
   if (rtt_updated) {
     has_valid_rtt_ = true;
   }