Enable QUIC for proxies only when QUIC is enabled

ios/chrome/browser/ios_chrome_io_thread.h

Index: ios/chrome/browser/ios_chrome_io_thread.h
diff --git a/ios/chrome/browser/ios_chrome_io_thread.h b/ios/chrome/browser/ios_chrome_io_thread.h
index f99b68f46e99323d399c51155d403593fa46d56b..3b4749ee1c43d05893cf4ff0b3c6c1168ad94841 100644
--- a/ios/chrome/browser/ios_chrome_io_thread.h
+++ b/ios/chrome/browser/ios_chrome_io_thread.h
@@ -145,7 +145,6 @@ class IOSChromeIOThread : public web::WebThreadDelegate {
     Optional<bool> enable_priority_dependencies;
 
     Optional<bool> enable_quic;
-    Optional<bool> enable_quic_for_proxies;
     Optional<bool> quic_always_require_handshake_confirmation;
     Optional<bool> quic_disable_connection_pooling;
     Optional<float> quic_load_server_info_timeout_srtt_multiplier;
@@ -193,10 +192,6 @@ class IOSChromeIOThread : public web::WebThreadDelegate {
 
   base::TimeTicks creation_time() const;
 
-  // Returns true if QUIC should be enabled for data reduction proxy as a result
-  // of a field trial.
-  static bool ShouldEnableQuicForDataReductionProxy();
-
  private:
   // Map from name to value for all parameters associate with a field trial.
   typedef std::map<std::string, std::string> VariationParameters;
@@ -271,10 +266,6 @@ class IOSChromeIOThread : public web::WebThreadDelegate {
   // Returns true if QUIC should be enabled as a result of a field trial.
   static bool ShouldEnableQuic(base::StringPiece quic_trial_group);
 
-  // Returns true if QUIC should be enabled for proxies as a result of a
-  // field trial.
-  static bool ShouldEnableQuicForProxies(base::StringPiece quic_trial_group);
-
   // Returns true if QUIC should always require handshake confirmation during
   // the QUIC handshake.
   static bool ShouldQuicAlwaysRequireHandshakeConfirmation(