Create an AutofillBackend interface

components/webdata/common/web_database_service.cc

Index: components/webdata/common/web_database_service.cc
diff --git a/components/webdata/common/web_database_service.cc b/components/webdata/common/web_database_service.cc
index baef346b113b8596a88d9a7d95756684ef0023e1..3c2ede573b8ff9991c323cb8e45a02b573671a5c 100644
--- a/components/webdata/common/web_database_service.cc
+++ b/components/webdata/common/web_database_service.cc
@@ -91,6 +91,13 @@ WebDatabase* WebDatabaseService::GetDatabaseOnDB() const {
   return wds_backend_->database();
 }
 
+scoped_refptr<WebDataServiceBackend> WebDatabaseService::GetBackend() const {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (!wds_backend_)
+    return NULL;
+  return wds_backend_;
+}
+
 void WebDatabaseService::ScheduleDBTask(
     const tracked_objects::Location& from_here,
     const WriteTask& task) {