Add unit-tests for ARCore device and related class

Bug: 837834
Change-Id: I7d3b81b0ae2290e58d18a623dc0f573afe83d955
Reviewed-on: https://chromium-review.googlesource.com/c/1197225
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Bill Orr <billorr@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Commit-Queue: Max Rebuschatis <lincolnfrog@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599584}
27 files changed