Revert of Remove support for Alt-Svc/Alternate Protocol Probability

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 022a625260c6f71f6968029cc47c78ee45d91a24..35c832a36c1dbad2255fd4b41aff57c91c450dce 100644
--- a/net/http/http_network_session.cc
+++ b/net/http/http_network_session.cc
@@ -98,6 +98,7 @@
       time_func(&base::TimeTicks::Now),
       parse_alternative_services(false),
       enable_alternative_service_with_different_host(false),
+      alternative_service_probability_threshold(1),
       enable_npn(true),
       enable_brotli(false),
       enable_quic(false),
@@ -243,6 +244,8 @@
 
   next_protos_.push_back(kProtoHTTP11);
 
+  http_server_properties_->SetAlternativeServiceProbabilityThreshold(
+      params.alternative_service_probability_threshold);
   http_server_properties_->SetMaxServerConfigsStoredInProperties(
       params.quic_max_server_configs_stored_in_properties);
 }
@@ -318,6 +321,8 @@
   dict->Set("connection_options", std::move(connection_options));
   dict->SetString("origin_to_force_quic_on",
                   params_.origin_to_force_quic_on.ToString());
+  dict->SetDouble("alternative_service_probability_threshold",
+                  params_.alternative_service_probability_threshold);
   dict->SetDouble("load_server_info_timeout_srtt_multiplier",
                   params_.quic_load_server_info_timeout_srtt_multiplier);
   dict->SetBoolean("enable_connection_racing",