Create a common base class for all the webdatas

chrome/browser/api/webdata/autofill_web_data_service.h

 // 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.
 
 #ifndef CHROME_BROWSER_API_WEBDATA_AUTOFILL_WEB_DATA_SERVICE_H_
 #define CHROME_BROWSER_API_WEBDATA_AUTOFILL_WEB_DATA_SERVICE_H_
 
 #include "chrome/browser/api/webdata/autofill_web_data.h"
 
 namespace content {
 class BrowserContext;
 }
 
 // API for Autofill web data.
 class AutofillWebDataService
     : public AutofillWebData,
       public WebDataServiceBase {
  public:
   // Retrieve an AutofillWebDataService for the given context.
   //
   // Can return NULL in some contexts.
-  static scoped_ptr<AutofillWebDataService> FromBrowserContext(
+  static scoped_refptr<AutofillWebDataService> FromBrowserContext(
       content::BrowserContext* context);
 
+ protected:
   virtual ~AutofillWebDataService() {}
 };
 
 #endif  // CHROME_BROWSER_API_WEBDATA_AUTOFILL_WEB_DATA_SERVICE_H_