Added support for multiple parameters to Extension API callbacks.

chrome/browser/extensions/api/media_gallery/media_gallery_api.cc

 // 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.
 
 // Implements the Chrome Extensions Media Galleries API.
 
 #include "chrome/browser/extensions/api/media_gallery/media_gallery_api.h"
 
 #include <string>
 #include <vector>
@@ skipping 41 matching lines @@
         "dirname", Value::CreateStringValue("_"));
     list->Append(dict_value);
 
     content::ChildProcessSecurityPolicy* policy =
         ChildProcessSecurityPolicy::GetInstance();
     if (!policy->CanReadFile(child_id, path))
       policy->GrantReadFile(child_id, path);
     policy->GrantReadFileSystem(child_id, fsid);
   }
 
-  result_.reset(list);
+  SetResult(list);
   return true;
 }
 
 OpenMediaGalleryManagerFunction::~OpenMediaGalleryManagerFunction() {}
 
 bool OpenMediaGalleryManagerFunction::RunImpl() {
   // TODO(vandebo) Open the Media Gallery Manager UI.
-  result_.reset(Value::CreateNullValue());
+  SetResult(Value::CreateNullValue());
   return true;
 }
 
 AssembleMediaFileFunction::~AssembleMediaFileFunction() {}
 
 bool AssembleMediaFileFunction::RunImpl() {
   // TODO(vandebo) Update the metadata and return the new file.
-  result_.reset(Value::CreateNullValue());
+  SetResult(Value::CreateNullValue());
   return true;
 }
 
 }  // namespace extensions