Make AddLocalizedStringsBulk() calls consistent.

- Pass in a constexpr array when possible.
- Use base::size().

Change-Id: I1e3073520d8fa4e4e2b6daf2854adf65648dd1c8
Reviewed-on: https://chromium-review.googlesource.com/c/1374468
Reviewed-by: Scott Chen <scottchen@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616444}