Update viz test context provider to provide GL integers required by Skia.

Bug: 644851
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I759a98701d50bad4347ae5f44e49a11a3b9cdd45
Reviewed-on: https://chromium-review.googlesource.com/1054526
Commit-Queue: Brian Salomon <bsalomon@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#562002}
1 file changed