Move extension API schema registration to ExtensionsClient.

extensions/common/extension_api.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_EXTENSION_API_H_
 #define EXTENSIONS_COMMON_EXTENSION_API_H_
 
 #include <map>
 #include <string>
 
@@ skipping 42 matching lines @@
   // "permission", or "api". The second part is the full name of the feature.
   static void SplitDependencyName(const std::string& full_name,
                                   std::string* feature_type,
                                   std::string* feature_name);
 
   // Creates a completely clean instance. Configure using RegisterSchema() and
   // RegisterDependencyProvider before use.
   ExtensionAPI();
   virtual ~ExtensionAPI();
 
+  // Add a (non-generated) API schema resource.
   void RegisterSchemaResource(const std::string& api_name, int resource_id);
 
+  // Add a FeatureProvider for APIs. The features are used to specify
+  // dependencies and constraints on the availability of APIs.
   void RegisterDependencyProvider(const std::string& name,
                                   const FeatureProvider* provider);
 
   // Returns true if the API feature |api| and all of its dependencies are
   // available in |context|.
   //
   // Depending on the configuration of |api| (in _api_features.json), either
   // |extension| or |url| (or both) may determine its availability, but this is
   // up to the configuration of the individual feature.
   Feature::Availability IsAvailable(const Feature& api,
@@ skipping 66 matching lines @@
   // FeatureProviders used for resolving dependencies.
   typedef std::map<std::string, const FeatureProvider*> FeatureProviderMap;
   FeatureProviderMap dependency_providers_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionAPI);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_EXTENSION_API_H_