extensions: Register 'app' and 'webstore' bindings only if they are available.

extensions/renderer/dispatcher.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_RENDERER_DISPATCHER_H_
 #define EXTENSIONS_RENDERER_DISPATCHER_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 214 matching lines @@
                               ScriptContext* context);
 
   // Inserts static source code into |source_map_|.
   void PopulateSourceMap();
 
   // Returns whether the current renderer hosts a platform app.
   bool IsWithinPlatformApp();
 
   bool IsSandboxedPage(const GURL& url) const;
 
+  bool IsApiAvailable(const std::string& api_name, ScriptContext* context);
+
   // Returns the Feature::Context type of context for a JavaScript context.
   Feature::Context ClassifyJavaScriptContext(
       const Extension* extension,
       int extension_group,
       const GURL& url,
       const blink::WebSecurityOrigin& origin);
 
   // Gets |field| from |object| or creates it as an empty object if it doesn't
   // exist.
   v8::Handle<v8::Object> GetOrCreateObject(const v8::Handle<v8::Object>& object,
@@ skipping 63 matching lines @@
   // the observer is destroyed before the UserScriptSet.
   ScopedObserver<UserScriptSetManager, UserScriptSetManager::Observer>
       user_script_set_manager_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(Dispatcher);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_DISPATCHER_H_