Chrome was using this format by accident for video decode surfaces, resulting
in a power usage regression.

BUG=angleproject:1662
BUG=691106

Change-Id: I3b9ac814f06c07490fceb88e8b087b235e5b25bf
Reviewed-on: https://chromium-review.googlesource.com/441950Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>