QUIC - FieldTrial parameters not do PreConnect if QUIC can do 0RTT.

chrome/browser/io_thread.h

Index: chrome/browser/io_thread.h
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index f156ebd5b0247f646e28ea1b2c7e04476f27cddd..510bc59f23268000a20212c4968f7bed886ada7f 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -231,6 +231,7 @@ class IOThread : public content::BrowserThreadDelegate {
     Optional<net::HostPortPair> origin_to_force_quic_on;
     Optional<bool> quic_close_sessions_on_ip_change;
     Optional<int> quic_idle_connection_timeout_seconds;
+    Optional<bool> quic_disable_preconnect_if_0rtt;
     bool enable_user_alternate_protocol_ports;
     // NetErrorTabHelper uses |dns_probe_service| to send DNS probes when a
     // main frame load fails with a DNS error in order to provide more useful
@@ -445,6 +446,10 @@ class IOThread : public content::BrowserThreadDelegate {
   static int GetQuicIdleConnectionTimeoutSeconds(
       const VariationParameters& quic_trial_params);
 
+  // Returns true if PreConnect should be disabled if QUIC can do 0RTT.
+  static bool ShouldQuicDisablePreConnectIfZeroRtt(
+      const VariationParameters& quic_trial_params);
+
   // Returns the maximum length for QUIC packets, based on any flags in
   // |command_line| or the field trial.  Returns 0 if there is an error
   // parsing any of the options, or if the default value should be used.