Use base::size() instead of arraysize in content/browser/indexed_db/

This swaps the deprecated 'arraysize' macro for base::size(), in the
//content/browser/indexed_db/ folder. No change to logic.

Bug: 837308
Change-Id: Ib0683aa3e6990115254aa2c9c83c65baf6a2f07e
Reviewed-on: https://chromium-review.googlesource.com/c/1379087
Reviewed-by: Joshua Bell <jsbell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#617168}
2 files changed