QUIC - Add back to code to experiment with delay_tcp_race. By default,

net/url_request/url_request_context_builder.h

Index: net/url_request/url_request_context_builder.h
diff --git a/net/url_request/url_request_context_builder.h b/net/url_request/url_request_context_builder.h
index 20ff0f33171fecfb288b54e4a025d5c236536fe5..2aa534f5865a68bf62ee02cab7fa1945651d5fd6 100644
--- a/net/url_request/url_request_context_builder.h
+++ b/net/url_request/url_request_context_builder.h
@@ -96,6 +96,7 @@ class NET_EXPORT URLRequestContextBuilder {
     bool enable_quic;
     std::string quic_user_agent_id;
     int quic_max_server_configs_stored_in_properties;
+    bool quic_delay_tcp_race;
     int quic_max_number_of_lossy_connections;
     std::unordered_set<std::string> quic_host_whitelist;
     bool quic_prefer_aes;
@@ -231,6 +232,10 @@ class NET_EXPORT URLRequestContextBuilder {
         quic_max_server_configs_stored_in_properties;
   }
 
+  void set_quic_delay_tcp_race(bool quic_delay_tcp_race) {
+    http_network_session_params_.quic_delay_tcp_race = quic_delay_tcp_race;
+  }
+
   void set_quic_max_number_of_lossy_connections(
       int quic_max_number_of_lossy_connections) {
     http_network_session_params_.quic_max_number_of_lossy_connections =