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 88d9beeb80a9b3a45004add6dcac583ac35b1f18..5c99d566e33313c7777b27c68dab477e8221ab81 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -11,6 +11,7 @@
 #include <map>
 #include <set>
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ -239,6 +240,7 @@ 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::unordered_set<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 +463,11 @@ class IOThread : public content::BrowserThreadDelegate {
   static bool ShouldQuicDisablePreConnectIfZeroRtt(
       const VariationParameters& quic_trial_params);
 
+  // Returns the set of hosts to whitelist for QUIC.
+  static std::unordered_set<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.