[Mac] Added Comments to TextSuggestionsTouchBarController Tests

Some TextSuggestionsTouchBarController unit tests were missing
comments. Comments were added where necessary.

Bug: 717553
Change-Id: I5e41114a5618899bba61d4867d17634ab151fcfc
Reviewed-on: https://chromium-review.googlesource.com/1178575
Reviewed-by: Sarah Chan <spqchan@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583886}
2 files changed