Display Alternate Protocol Probability Threshold in net-internals.

net/http/http_network_session.cc

Index: net/http/http_network_session.cc
diff --git a/net/http/http_network_session.cc b/net/http/http_network_session.cc
index 9c2cc14a6404d75321781d8dadaf389a6bfedd83..6dd06ea224ad36b8800a7eb2f0de7d01a7864502 100644
--- a/net/http/http_network_session.cc
+++ b/net/http/http_network_session.cc
@@ -268,6 +268,8 @@ base::Value* HttpNetworkSession::QuicInfoToValue() const {
                    params_.enable_quic_time_based_loss_detection);
   dict->SetString("origin_to_force_quic_on",
                   params_.origin_to_force_quic_on.ToString());
+  dict->SetDouble("alternate_protocol_probability_threshold",
+                  params_.alternate_protocol_probability_threshold);
   return dict;
 }