Chrome uses external textures as part of its hardware video decode paths
on Android.

BUG=angleproject:2507

Change-Id: I2af608f84a99843c99a16dcfb9fb2fa28cc8fbb6
Reviewed-on: https://chromium-review.googlesource.com/c/1361480Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>