Refactor all the UMA tracking in Password Protection

Move all the UMA logging logic into a separate util file.
And make all relevant enums to enum classes.
No behavior changes.

Bug: 854314
Change-Id: If6035cc1ee86faa4f1aaf003318f72dc44660814
Reviewed-on: https://chromium-review.googlesource.com/1145768
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Reviewed-by: Varun Khaneja <vakh@chromium.org>
Commit-Queue: Jialiu Lin <jialiul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578339}
25 files changed