Revert of Make NVPR a GL context option instead of a GL context

Revert of Make NVPR a GL context option instead of a GL context (patchset #9 id:160001 of https://codereview.chromium.org/1448883002/ )

Reason for revert:
Breaking bots:
http://build.chromium.org/p/client.skia/builders/Test-Ubuntu-GCC-ShuttleA-GPU-GTX660-x86_64-Debug/builds/3238/steps/dm/logs/stdio

Original issue's description:
> Make NVPR a GL context option instead of a GL context
> 
> Make NVPR a GL context option instead of a GL context.
> This may enable NVPR to be run with command buffer
> interface.
> 
> No functionality change in DM or nanobench. NVPR can
> only be run with normal GL APIs.
> 
> BUG=skia:2992
> 
> Committed: https://skia.googlesource.com/skia/+/eeebdb538d476c1bfc8b63a946094ca1b505ecd1
> 
> Committed: https://skia.googlesource.com/skia/+/64492c43c3faee7ab0f69b1c84e0267616f85e52

TBR=mtklein@google.com,jvanverth@google.com,scroggo@google.com,kkinnunen@nvidia.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:2992

[bsalomon, 2015-12-09 15:03:47]

Created Revert of Make NVPR a GL context option instead of a GL context

[commit-bot: I haz the power, 2015-12-09 15:04:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1511613004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1511613004/1

[commit-bot: I haz the power, 2015-12-09 15:04:19]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-12-09 15:04:20]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-12-09 15:04:23]

The CQ bit was unchecked by commit-bot@chromium.org