Implement API features for the Extension API feature system

chrome/common/extensions/features/manifest_feature.h

 // Copyright (c) 2012 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 CHROME_COMMON_EXTENSIONS_FEATURES_MANIFEST_FEATURE_H_
 #define CHROME_COMMON_EXTENSIONS_FEATURES_MANIFEST_FEATURE_H_
 
 #include "chrome/common/extensions/features/simple_feature.h"
 
 namespace extensions {
 
 class ManifestFeature : public SimpleFeature {
  public:
   ManifestFeature();
   virtual ~ManifestFeature();
 
   virtual Feature::Availability IsAvailableToContext(
       const Extension* extension,
       Feature::Context context,
       const GURL& url,
       Feature::Platform platform) const OVERRIDE;
+
+  virtual std::string Parse(const DictionaryValue* value) OVERRIDE;
 };
 
 }  // extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_FEATURES_MANIFEST_FEATURE_H_