ServiceWorker: Add TIMEOUT event status to return it to the browser

This is to align with the behavior of the non servicified path.

Bug: 852658
Change-Id: I0a95231d6cc8e0c8745aaede523c54100c5e1603
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1511096
Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Auto-Submit: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639860}
7 files changed