Generalize NativeBuffer11::setData. We can replace this method with a base class method which uses our implementation of "map". This allows us to reuse setData in other mappable buffer storage types. BUG=angle:912 Change-Id: I7848cb9440b806364d9b2a6e2251323e53206921 Reviewed-on: https://chromium-review.googlesource.com/249182 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Brandon Jones <bajones@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>