Add tests to validate gamepad vibration API

BUG=749295

Change-Id: I84a038a9b3e054ac7a049e6df2cb23b82f9139ec
Reviewed-on: https://chromium-review.googlesource.com/734002
Reviewed-by: Brandon Jones <bajones@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Matt Reynolds <mattreynolds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527860}
3 files changed