Added check for behavior feature existense

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 <map>
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 
 namespace extensions {
 
+class Extension;

[benwells, 2016/04/14 06:36:15]

It's nice that this file doesn't depend on Extension. It's also a bit weird now
that the behavior features don't follow the same pattern of the other features.

Can you revert the changes in this file, but ad a comment above Get*Feature that
the features can be null if JSON files are corrupted, and just put null checks
in the callsites to GetBehaviorFeature?

 class Feature;
 
 using FeatureMap = std::map<std::string, scoped_ptr<Feature>>;
 
 // Implemented by classes that can vend features.
 class FeatureProvider {
  public:
   FeatureProvider() {}
   virtual ~FeatureProvider() {}
 
   //
   // Static helpers.
   //
 
   // Gets a FeatureProvider for a specific type, like "permission".
   static const FeatureProvider* GetByName(const std::string& name);
 
   // Directly access the common FeatureProvider types.
   // Each is equivalent to GetByName('featuretype').
   static const FeatureProvider* GetAPIFeatures();
   static const FeatureProvider* GetManifestFeatures();
   static const FeatureProvider* GetPermissionFeatures();
   static const FeatureProvider* GetBehaviorFeatures();
 
   // Directly get Features from the common FeatureProvider types.
   // Each is equivalent to GetByName('featuretype')->GetFeature(name).
   static const Feature* GetAPIFeature(const std::string& name);
   static const Feature* GetManifestFeature(const std::string& name);
   static const Feature* GetPermissionFeature(const std::string& name);
-  static const Feature* GetBehaviorFeature(const std::string& name);
+
+  // Check if behavior feature exists and is available for extension.
+  // Feature existence should be checked as sometimes JSONReader fails to read
+  // resource file correctly. See http://crbug.com/176381
+  static bool BehaviorFeatureIsAvailable(const std::string& name,
+                                         const Extension* extension);
 
   //
   // Instance methods.
   //
 
   // Returns the feature with the specified name.
   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) const = 0;
 
   // Returns the features inside the |parent| namespace, recursively.
   virtual std::vector<Feature*> GetChildren(const Feature& parent) const = 0;
 
   // Returns a map containing all features described by this instance.
   virtual const FeatureMap& GetAllFeatures() const = 0;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_PROVIDER_H_