Enable QUIC for proxies only when QUIC is enabled

ios/chrome/browser/ios_chrome_io_thread.mm

Index: ios/chrome/browser/ios_chrome_io_thread.mm
diff --git a/ios/chrome/browser/ios_chrome_io_thread.mm b/ios/chrome/browser/ios_chrome_io_thread.mm
index a3a10992e68bc6b9a282d641dfb6ddc95d082e7c..f998fd68b371e0b8f558cc17b01f41e75a7c119b 100644
--- a/ios/chrome/browser/ios_chrome_io_thread.mm
+++ b/ios/chrome/browser/ios_chrome_io_thread.mm
@@ -645,7 +645,6 @@ void IOSChromeIOThread::InitializeNetworkSessionParamsFromGlobals(
       &params->enable_priority_dependencies);
 
   globals.enable_quic.CopyToIfSet(&params->enable_quic);
-  globals.enable_quic_for_proxies.CopyToIfSet(&params->enable_quic_for_proxies);
   globals.quic_always_require_handshake_confirmation.CopyToIfSet(
       &params->quic_always_require_handshake_confirmation);
   globals.quic_disable_connection_pooling.CopyToIfSet(
@@ -752,8 +751,6 @@ void IOSChromeIOThread::ConfigureQuicGlobals(
     IOSChromeIOThread::Globals* globals) {
   bool enable_quic = ShouldEnableQuic(quic_trial_group);
   globals->enable_quic.set(enable_quic);
-  bool enable_quic_for_proxies = ShouldEnableQuicForProxies(quic_trial_group);
-  globals->enable_quic_for_proxies.set(enable_quic_for_proxies);
 
   if (ShouldQuicEnableAlternativeServicesForDifferentHost(quic_trial_params)) {
     globals->enable_alternative_service_with_different_host.set(true);
@@ -826,16 +823,6 @@ bool IOSChromeIOThread::ShouldEnableQuic(base::StringPiece quic_trial_group) {
          quic_trial_group.starts_with(kQuicFieldTrialHttpsEnabledGroupName);
 }
 
-bool IOSChromeIOThread::ShouldEnableQuicForProxies(
-    base::StringPiece quic_trial_group) {
-  return ShouldEnableQuic(quic_trial_group) ||
-         ShouldEnableQuicForDataReductionProxy();
-}
-
-bool IOSChromeIOThread::ShouldEnableQuicForDataReductionProxy() {
-  return data_reduction_proxy::params::IsIncludedInQuicFieldTrial();
-}
-
 net::QuicTagVector IOSChromeIOThread::GetQuicConnectionOptions(
     const VariationParameters& quic_trial_params) {
   VariationParameters::const_iterator it =