Use GetThreatSource instead of hardcoding ThreatSource.

Removes a long time TODO.

Bug: 764965
Change-Id: I0e1eeb2f4fb824effc73af75ebbd6db0b754a2a1
Reviewed-on: https://chromium-review.googlesource.com/666120
Reviewed-by: Jialiu Lin <jialiul@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Commit-Queue: Varun Khaneja <vakh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501822}
4 files changed