Add end2end tests and unittests.

BUG=angleproject:970

Change-Id: Ie8306971730a793f08dfd09ead1bfd6ff3e4623d
Reviewed-on: https://chromium-review.googlesource.com/291260Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>