GitLab

Ensures that a preview is not shown when the previews server cannot be
reached.

Bug: 864656
Change-Id: I417e7988bce7509ddbc31dfadfd48d91f1434e16
Reviewed-on: https://chromium-review.googlesource.com/1213664Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589714}