Port the MultiTexture sample to the new sample framework. BUG=angle:521 Change-Id: I72f063664b43d3cfafe03c8f060076596bedea0f Reviewed-on: https://chromium-review.googlesource.com/188194 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>