IMO, we should make ApplicationStorage working in DB thread in furture, otherwise, it may block the ApplicationService daemon. But for current code base, running in ui thread is enough. I've a concern that it's not easy to reuse the ApplicationStorage code in a divided xwalk application manage tool when using multi-thread model. So let's change it when needed, and fire a bug in JIRA to trace it. @shaochangbin @pozdnyakov wdyt?