Async Cookies: More service worker subscription tests.

Bug: 729800
Change-Id: Ie216054a92e223c29120226b645b2c10b208dde0
Reviewed-on: https://chromium-review.googlesource.com/1073080
Reviewed-by: Victor Costan <pwnall@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569930}
6 files changed