This is a reland of 047ba2f8

TBR=dcastagna@chromium.org,piman@chromium.org,ericrk@chromium.org,danakj@chromium.org

Original change's description:
> Reland "Switching all ui/gl dependent tests to SwiftShader"
>
> This is a reland of 9f1eb0ba
>
> The only change from the original cl is in cc/test/layer_tree_test.cc,
> so TBRing reviewers who approved other parts of this cl.
> TBR=dcastagna@chromium.org,piman@chromium.org,ericrk@chromium.org
>
> Original change's description:
> > Switching all ui/gl dependent tests to SwiftShader
> >
> > This cl's switches cc_unittests and viz_unittests from OSMesa
> > to SwiftShader and fixes other issues related to that change.
> >
> > Bug chromium:848035
> >
> > 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;master.tryserver.blink:linux_trusty_blink_rel
> > Change-Id: Ib1b58e02d4df4a687ef7be57284c06097bdeca94
> > Reviewed-on: https://chromium-review.googlesource.com/1070490
> > Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
> > Reviewed-by: danakj <danakj@chromium.org>
> > Reviewed-by: Antoine Labour <piman@chromium.org>
> > Reviewed-by: Eric Karl <ericrk@chromium.org>
> > Commit-Queue: Alexis Hétu <sugoi@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#572442}
>
> Change-Id: I85f723ed8a8f7d981a9652cd7979c54d0f1248ae
> 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;master.tryserver.blink:linux_trusty_blink_rel
> Reviewed-on: https://chromium-review.googlesource.com/1125899
> Commit-Queue: Alexis Hétu <sugoi@chromium.org>
> Reviewed-by: Alexis Hétu <sugoi@chromium.org>
> Reviewed-by: danakj <danakj@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#572623}

Change-Id: I8e0a113f356ea997ee9dff45e3cd0d465f349006
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;master.tryserver.blink:linux_trusty_blink_rel
Reviewed-on: https://chromium-review.googlesource.com/1127419
Commit-Queue: Alexis Hétu <sugoi@chromium.org>
Reviewed-by: Alexis Hétu <sugoi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579950}