Pass a Feature* to IsAnyFeatureAvailableToContext instead of a string name.

extensions/common/features/feature_provider.h

 // Copyright 2013 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_FEATURE_PROVIDER_H_
 #define EXTENSIONS_COMMON_FEATURES_FEATURE_PROVIDER_H_
 
 #include <string>
 #include <vector>
 
 namespace extensions {
 
 class Feature;
 
 // Implemented by classes that can vend features.
 class FeatureProvider {
  public:
   FeatureProvider() {}
   virtual ~FeatureProvider() {}
 
   // Returns the feature with the specified name.
-  virtual Feature* GetFeature(const std::string& name) = 0;
+  virtual Feature* GetFeature(const std::string& name) const = 0;
 
   // Returns the parent feature of |feature|, or NULL if there isn't one.
-  virtual Feature* GetParent(Feature* feature) = 0;
+  virtual Feature* GetParent(Feature* feature) const = 0;
 
   // Returns all features described by this instance.
-  virtual const std::vector<std::string>& GetAllFeatureNames() = 0;
+  virtual const std::vector<std::string>& GetAllFeatureNames() const = 0;
 
   // Gets a feature provider for a specific feature type, like "permission".
   static FeatureProvider* GetByName(const std::string& name);
 
   // Directly access the common feature types.
   static FeatureProvider* GetAPIFeatures();
   static FeatureProvider* GetManifestFeatures();
   static FeatureProvider* GetPermissionFeatures();
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_PROVIDER_H_