- Switch #define constant to static const
- Remove unnecessary Internal version of GetCategoryGroupEnabled()
- Fix a typo in a comment

Change-Id: I4af71dc62c7c4742bdfbcaa1ad336298eb325c42
Reviewed-on: https://chromium-review.googlesource.com/c/1477221Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59708}