Win 10 Notifications: Implement reminders (requireInteraction).

Also add a null timestamp test.

Bug: 734095
Change-Id: Ib51c0f05e685c29cf282122e6e1b5e62aff70771
Reviewed-on: https://chromium-review.googlesource.com/739385
Commit-Queue: Finnur Thorarinsson <finnur@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514241}
3 files changed