GitLab

In the case that the backing VR service is not available the call will now
resolve to an empty array.

BUG=678283
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2614873002
Cr-Commit-Position: refs/heads/master@{#442117}