[Extensions] Remove JSONFeatureProvider, SimpleFeature::Parse

extensions/common/features/json_feature_provider.h

-// Copyright 2014 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.
-
-#ifndef EXTENSIONS_COMMON_FEATURES_JSON_FEATURE_PROVIDER_H_
-#define EXTENSIONS_COMMON_FEATURES_JSON_FEATURE_PROVIDER_H_
-
-#include "extensions/common/features/base_feature_provider.h"
-
-namespace base {
-class DictionaryValue;
-}
-
-namespace extensions {
-class SimpleFeature;
-
-// Reads Features out of a simple JSON file description.
-class JSONFeatureProvider : public BaseFeatureProvider {
- public:
-  typedef SimpleFeature* (*FeatureFactory)();
-
-  // Creates a new JSONFeatureProvider. Pass null to |factory| to have the
-  // provider create plain old Feature instances.
-  JSONFeatureProvider(const base::DictionaryValue& root,
-                      FeatureFactory factory);
-  ~JSONFeatureProvider() override;
-
- private:
-  FeatureFactory factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(JSONFeatureProvider);
-};
-
-}  // namespace extensions
-
-#endif  // EXTENSIONS_COMMON_FEATURES_JSON_FEATURE_PROVIDER_H_