Revert of Re-land: content: Enable native GpuMemoryBuffers by default on MacOSX.

Revert of Re-land: content: Enable native GpuMemoryBuffers by default on MacOSX. (patchset #7 id:120001 of https://codereview.chromium.org/1165823003/)

Reason for revert:
Windows get stuck displaying all white for content area.

https://code.google.com/p/chromium/issues/detail?id=509917

Original issue's description:
> Re-land: content: Enable native GpuMemoryBuffers by default on MacOSX.
>
> This eliminates the need for texture uploads to initialize
> tile textures on MacOSX.
>
> BUG=486922
>
> Committed: https://crrev.com/aff70f7fcd9be4d503c97f93f5fae31a43ec3e23
> Cr-Commit-Position: refs/heads/master@{#337657}

TBR=avi@chromium.org,ccameron@chromium.org,piman@chromium.org,reveman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=486922
Committed: https://crrev.com/af16d8d226f8bf839eae32779fea2d463645b1ea
Cr-Commit-Position: refs/heads/master@{#339363}

[erikchen, 2015-07-18 00:17:10]

Created Revert of Re-land: content: Enable native GpuMemoryBuffers by default on
MacOSX.

[commit-bot: I haz the power, 2015-07-18 00:17:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1232083007/1

[commit-bot: I haz the power, 2015-07-18 00:18:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-18 00:21:08]

Patchset 1 (id:??) landed as
https://crrev.com/af16d8d226f8bf839eae32779fea2d463645b1ea
Cr-Commit-Position: refs/heads/master@{#339363}