Add brotli content-encoding filter.

content/public/common/content_features.h

 // Copyright 2015 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.
 
 // This file defines all the public base::FeatureList features for the content
 // module.
 
 #ifndef CONTENT_PUBLIC_COMMON_CONTENT_FEATURES_H_
 #define CONTENT_PUBLIC_COMMON_CONTENT_FEATURES_H_
 
 #include "base/feature_list.h"
 #include "build/build_config.h"
 #include "content/common/content_export.h"
 
 namespace features {
 
 // All features in alphabetical order. The features should be documented
 // alongside the definition of their values in the .cc file.
+CONTENT_EXPORT extern const base::Feature kBrotliEncoding;
 CONTENT_EXPORT extern const base::Feature kDownloadResumption;
 CONTENT_EXPORT extern const base::Feature kExperimentalFramework;
 
 #if defined(OS_ANDROID)
 CONTENT_EXPORT extern const base::Feature kSeccompSandboxAndroid;
 #endif  // defined(OS_ANDROID)
 
 // DON'T ADD RANDOM STUFF HERE. Put it in the main section above in
 // alphabetical order, or in one of the ifdefs (also in order in each section).
 
 }  // namespace features
 
 #endif  // CONTENT_PUBLIC_COMMON_CONTENT_FEATURES_H_