Don't store empty values for autofill

chrome/browser/autofill_manager.cc

 // 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.
 
 #include "chrome/browser/autofill_manager.h"
 
 #include "base/string_util.h"
 #include "chrome/browser/profile.h"
 #include "chrome/browser/tab_contents/web_contents.h"
 #include "chrome/common/pref_names.h"
+#include "chrome/common/pref_service.h"
+
+// static
+void AutofillManager::RegisterUserPrefs(PrefService* prefs) {
+  prefs->RegisterBooleanPref(prefs::kFormAutofillEnabled, true);
+}
 
 AutofillManager::AutofillManager(WebContents* web_contents) :
     web_contents_(web_contents),
     pending_query_handle_(0),
     node_id_(0),
     request_id_(0) {
   form_autofill_enabled_.Init(prefs::kFormAutofillEnabled,
       profile()->GetPrefs(), NULL);
 }
 
@@ skipping 80 matching lines @@
     const AutofillForm& form) {
   if (!*form_autofill_enabled_)
     return;
 
   if (profile()->IsOffTheRecord())
     return;
 
   profile()->GetWebDataService(Profile::EXPLICIT_ACCESS)->
       AddAutofillFormElements(form.elements);
 }