Use-case: Service Worker cache population and synchronization

If and when browser support for webpackage arrives, batch cache synchronization [1] or cache initialization [2] might be good use-cases, especially in the context of Service Worker. Using some sort of content negotiation mechanism, Service Worker might be able to ask the server for a webpackage that at least contains desired request URL(s). By unpacking the response and populating the cache, it can serve subsequent requests pretty quickly. What will be packed in the response is something that can be negotiated using some means or the server can decide as it does in case of HTTP/2 Server Hints (prefetch).

[1] https://github.com/WICG/BackgroundSync [2] https://developer.mozilla.org/en-US/docs/Web/API/Cache/addAll