Since Chrome 22 the non-persistent background pages aka event pages have been preferred over persistent background pages.

Also, the non-persistent background page model is similar to the emerging ServiceWorker (to be standardized) in that it can be killed anytime by the system. In order to ensure smooth migration to ServiceWorker and maximize the reuse of code, it would make sense to implement the non-persistent background page as early as possible.

@kenchris the JIRA issue related to event pages is at https://crosswalk-project.org/jira/browse/XWALK-2