Add an ANGLE sample framework. BUG=angle:521 Change-Id: If1fc6198dbbe44f0ade5539cff540e3e086f2a3b Reviewed-on: https://chromium-review.googlesource.com/188722 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>