Add a whitelist for QUIC hosts.

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 b7ca041b63978eeeddf1ec4473125169e29ce5d3..f7c3ac2951371e9d76c6e75d8dbb7b7b03814394 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -239,6 +239,7 @@ class IOThread : public content::BrowserThreadDelegate {
     Optional<bool> quic_close_sessions_on_ip_change;
     Optional<int> quic_idle_connection_timeout_seconds;
     Optional<bool> quic_disable_preconnect_if_0rtt;
+    std::vector<std::string> quic_host_whitelist;
     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
@@ -461,6 +462,11 @@ class IOThread : public content::BrowserThreadDelegate {
   static bool ShouldQuicDisablePreConnectIfZeroRtt(
       const VariationParameters& quic_trial_params);
 
+  // Returns the set of hosts to whitelist for QUIC.
+  static std::vector<std::string> GetQuicHostWhitelist(
+      const base::CommandLine& command_line,
+      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.