This class is not D3D-specific so can be shared among other
back-ends, or other parts of the ANGLE codebase.

Change-Id: Ie00760eb5dae4db52e465ee7a2f97789bae8c0b0
Reviewed-on: https://chromium-review.googlesource.com/246500Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>