Add a function to ServiceWorkerContextWrapper which starts a service worker and keeps it alive indefinitely.

This is only for use in ChromeOS for the Android Web Messages native integration.

Change-Id: Id2357f54078c12db0ad25cd9fe0622d57e34a064
Bug: 850823
Reviewed-on: https://chromium-review.googlesource.com/1119580
Reviewed-by: Kinuko Yasuda <[email protected]>
Reviewed-by: Matt Falkenhagen <[email protected]>
Reviewed-by: Steven Holte <[email protected]>
Commit-Queue: Jon Mann <[email protected]>
Cr-Commit-Position: refs/heads/master@{#582331}
17 files changed