Port the MipMap2D sample to the new sample framework. BUG=angle:521 Change-Id: I3b1d3a02214850bf52c1d5c468f5696076065b88 Reviewed-on: https://chromium-review.googlesource.com/188193 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>