Allow QUIC's BBR congestion control to be negotiated in the crypto

net/quic/quic_sent_packet_manager.cc

Index: net/quic/quic_sent_packet_manager.cc
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index eaf66bd0fe94f396c79424ca28eb6b4a887c36b2..e8a6edd2851b9cfe68e78146d63bd864a477e151 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -82,7 +82,13 @@ void QuicSentPacketManager::SetFromConfig(const QuicConfig& config) {
     rtt_stats_.set_initial_rtt_us(min(kMaxInitialRoundTripTimeUs,
                                       config.ReceivedInitialRoundTripTimeUs()));
   }
-  if (config.congestion_control() == kPACE) {
+  // TODO(ianswett): BBR is currently a server only feature.
+  if (config.HasReceivedCongestionOptions() &&
+      ContainsQuicTag(config.ReceivedCongestionOptions(), kTBBR)) {
+    send_algorithm_.reset(
+        SendAlgorithmInterface::Create(clock_, &rtt_stats_, kTCPBBR, stats_));
+  }
+  if (config.congestion_feedback() == kPACE) {
     MaybeEnablePacing();
   }
   if (config.HasReceivedLossDetection() &&