Implement WebViewDatabase's hasFormData API for chromium based webview.

components/autofill/browser/webdata/autofill_webdata_backend.h

 // Copyright 2013 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 COMPONENTS_AUTOFILL_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_
 #define COMPONENTS_AUTOFILL_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "components/autofill/browser/webdata/autofill_webdata.h"
@@ skipping 26 matching lines @@
                                      WebDatabase* db);
 
   // Returns a vector of values which have been entered in form input fields
   // named |name|.
   scoped_ptr<WDTypedResult> GetFormValuesForElementName(
       const base::string16& name,
       const base::string16& prefix,
       int limit,
       WebDatabase* db);
 
+  // Returns true if there are any elements in the form.
+  scoped_ptr<WDTypedResult> HasFormElements(WebDatabase* db);
+
   // Removes form elements recorded for Autocomplete from the database.
   WebDatabase::State RemoveFormElementsAddedBetween(
       const base::Time& delete_begin,
       const base::Time& delete_end,
       WebDatabase* db);
 
   // Removes expired form elements recorded for Autocomplete from the database.
   WebDatabase::State RemoveExpiredFormElements(WebDatabase* db);
 
   // Removes the Form-value |value| which has been entered in form input fields
@@ skipping 62 matching lines @@
   void DestroyAutofillCreditCardResult(const WDTypedResult* result);
 
   ObserverList<AutofillWebDataServiceObserverOnDBThread> db_observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(AutofillWebDataBackend);
 };
 
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_BROWSER_WEBDATA_AUTOFILL_WEBDATA_BACKEND_H_