Add a whitelist for QUIC hosts.

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 150a758270be19cc738ea239c88449c46dbd9ef5..fd438c0da1e52336418127ce2831c970b325aaea 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -1178,6 +1178,8 @@ void IOThread::InitializeNetworkSessionParamsFromGlobals(
       &params->quic_idle_connection_timeout_seconds);
   globals.quic_disable_preconnect_if_0rtt.CopyToIfSet(
       &params->quic_disable_preconnect_if_0rtt);
+  if (!globals.quic_host_whitelist.empty())
+    params->quic_host_whitelist = globals.quic_host_whitelist;
 
   globals.origin_to_force_quic_on.CopyToIfSet(
       &params->origin_to_force_quic_on);
@@ -1317,6 +1319,8 @@ void IOThread::ConfigureQuicGlobals(
     }
     globals->quic_disable_preconnect_if_0rtt.set(
         ShouldQuicDisablePreConnectIfZeroRtt(quic_trial_params));
+    globals->quic_host_whitelist =
+        GetQuicHostWhitelist(command_line, quic_trial_params);
   }
 
   size_t max_packet_length = GetQuicMaxPacketLength(command_line,
@@ -1576,6 +1580,24 @@ bool IOThread::ShouldQuicDisablePreConnectIfZeroRtt(
       "true");
 }
 
+std::unordered_set<std::string> IOThread::GetQuicHostWhitelist(
+    const base::CommandLine& command_line,
+    const VariationParameters& quic_trial_params) {
+  std::string whitelist;
+  if (command_line.HasSwitch(switches::kQuicHostWhitelist)) {
+    whitelist = command_line.GetSwitchValueASCII(switches::kQuicHostWhitelist);
+  } else {
+    whitelist = GetVariationParam(quic_trial_params, "quic_host_whitelist");
+  }
+  std::unordered_set<std::string> hosts;
+  for (const std::string& host :base::SplitString(whitelist, ",",
+                                                  base::TRIM_WHITESPACE,
+                                                  base::SPLIT_WANT_ALL)) {
+    hosts.insert(host);
+  }
+  return hosts;
+}
+
 size_t IOThread::GetQuicMaxPacketLength(
     const base::CommandLine& command_line,
     const VariationParameters& quic_trial_params) {