Just the bare minimum implementation for end2end tests to run.

BUG=angleproject:1362
TEST=angle_end2end_tests on Nexus 5X

Change-Id: I92293e0f8bdc2ffaa5d4661927750d7cb3d931e6
Reviewed-on: https://chromium-review.googlesource.com/349353Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>