Add a QUIC tag to connection options to allow negotiating 1 connection

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 b1e04a9723db787219d95ad91d84f5fbd4fac99e..4c5307562d3d833847802f061ec295b4675749ff 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -126,6 +126,15 @@ void QuicSentPacketManager::SetFromConfig(const QuicConfig& config) {
              ContainsQuicTag(config.SendConnectionOptions(), kPACE)) {
     EnablePacing();
   }
+  if (is_server_) {
+    if (config.HasReceivedConnectionOptions() &&
+        ContainsQuicTag(config.ReceivedConnectionOptions(), k1CON)) {
+      send_algorithm_->SetNumEmulatedConnections(1);
+    }
+  } else if (config.HasSendConnectionOptions() &&
+             ContainsQuicTag(config.SendConnectionOptions(), k1CON)) {
+    send_algorithm_->SetNumEmulatedConnections(1);
+  }
   // TODO(ianswett): Remove the "HasReceivedLossDetection" branch once
   // the ConnectionOptions code is live everywhere.
   if (config.HasReceivedConnectionOptions() &&