As I mentioned in the forum, I didn't grok the whole code -- merely relied on your #if UNITY_METRO lines doing the right thing.
I include a test-case to check the logic documenting expected needs (though I'm not positive about the Metro stuff). Per the comment at the top of the test, it is only enabled with a define so shouldn't impact those not working on the UTT. Hope this is a reasonable precedent. Obviously it's not a sample test so didn't fit there.