Move GenerateMip to the D3D folder. BUG=angle:681 Change-Id: Icdffe7eb8f975ee0966e9fb241835ac541eb39f0 Reviewed-on: https://chromium-review.googlesource.com/238477 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>