Include a preliminary implementation of a simple benchmark app.

BUG=angle:705

Change-Id: I627450f6fdf01ed2054a50bd2327b7b9128c86f5
Reviewed-on: https://chromium-review.googlesource.com/214230Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>