Revert of Add command_buffer_gles2

Revert of Add command_buffer_gles2 (patchset #13 id:290001 of https://codereview.chromium.org/1220883008/ )

Reason for revert:
Broke the gles2_conform_tests, visible on the GPU FYI waterfall.

Original issue's description:
> Add command_buffer_gles2
>
> This is a very simple library that exposes some egl-like functions that
> can be used by skia to use the command buffer as a backend for their
> tests
>
> Committed: https://crrev.com/604b615373e4e9f873db37cef9c6416176fc35f3
> Cr-Commit-Position: refs/heads/master@{#346251}
>
> Committed: https://crrev.com/efa3a446183fbbff2034a03989f12543d0713e39
> Cr-Commit-Position: refs/heads/master@{#346840}

TBR=piman@chromium.org,dpranke@chromium.org,sievers@chromium.org,hendrikw@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/3adf304a1210759ccb20edc2bee8f59e48f03712
Cr-Commit-Position: refs/heads/master@{#346914}

[Jamie Madill, 2015-09-02 14:34:33]

Created Revert of Add command_buffer_gles2

[commit-bot: I haz the power, 2015-09-02 14:34:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1319453005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1319453005/1

[commit-bot: I haz the power, 2015-09-02 14:35:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-02 14:36:54]

Patchset 1 (id:??) landed as
https://crrev.com/3adf304a1210759ccb20edc2bee8f59e48f03712
Cr-Commit-Position: refs/heads/master@{#346914}