Adds feature flag for chrome-proxy-ect header (default off)

components/data_reduction_proxy/core/common/data_reduction_proxy_features.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_features.h"
 
 namespace data_reduction_proxy {
 namespace features {
 
 // Enables the Data Reduction Proxy menu item in the main menu rather than under
 // Settings on Android.
 const base::Feature kDataReductionMainMenu{"DataReductionProxyMainMenu",
                                            base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Enables sending the Effective Connection Type header to the Data Reduction
+// Proxy.
+const base::Feature kDataReductionProxyECTHeader{
+    "DataReductionProxyECTHeader", base::FEATURE_DISABLED_BY_DEFAULT};
+
+bool IsDataReductionProxyECTHeaderEnabled() {
+  return base::FeatureList::IsEnabled(kDataReductionProxyECTHeader);
+}
+
 }  // namespace features
 }  // namespace data_reduction_proxy