Making the Program own the attribs, and the Impl only see a read-only copy cleans up the Impl object. It also allows us to more cleanly isolate certain coded into D3D. BUG=angleproject:1123 Change-Id: I469051eb066fc56e55282affa2d5398b394ab8d2 Reviewed-on: https://chromium-review.googlesource.com/293826Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org>
