The type of the share handle depends on the implementation.

BUG=angle:658

Change-Id: Id801f3d0c1e3def7cae5cbd88e7a7032b2f6d8fa
Reviewed-on: https://chromium-review.googlesource.com/242050Reviewed-by: Brandon Jones <bajones@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>