GitLab

- Make some member variables const.
- Initialize member variables in the header when possible.
- Make GetLanguage() const.
- Fix various nits.

Change-Id: Ib508052f2491955cc41554204a2010299bc2d4ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2092879Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Reviewed-by: Chris Hall <chrishall@chromium.org>
Commit-Queue: Chris Hall <chrishall@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748593}