Don't store empty values for autofill

chrome/browser/autofill_manager.h

 // Copyright (c) 2006-2008 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_AUTOFILL_MANAGER_H_
 #define CHROME_BROWSER_AUTOFILL_MANAGER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 24 matching lines @@
   void FetchValuesForName(const std::wstring& name,
                           const std::wstring& prefix,
                           int limit,
                           int64 node_id,
                           int request_id);
 
   // WebDataServiceConsumer implementation.
   virtual void OnWebDataServiceRequestDone(WebDataService::Handle h,
                                            const WDTypedResult* result);
 
+  static void RegisterUserPrefs(PrefService* prefs);
+
  private:
   void StoreFormEntriesInWebDatabase(const AutofillForm& form);
 
   WebContents* web_contents_;
 
   BooleanPrefMember form_autofill_enabled_;
 
   // When the manager makes a request from WebDataService, the database
   // is queried on another thread, we record the query handle until we
   // get called back.
   WebDataService::Handle pending_query_handle_;
   int64 node_id_;
   int request_id_;
 
   DISALLOW_COPY_AND_ASSIGN(AutofillManager);
 };
 
 #endif  // CHROME_BROWSER_AUTOFILL_MANAGER_H_