Revert of content: Fix single process support for native GpuMemoryBuffers.

Revert of content: Fix single process support for native GpuMemoryBuffers. (patchset #1 id:1 of https://codereview.chromium.org/1221473003/)

Reason for revert:
Speculative revert to see if this is what broke XP Tests (1).

Original issue's description:
> content: Fix single process support for native GpuMemoryBuffers.
> 
> Also add the startup message filter for CreateGpuMemoryBuffer
> messages in single process mode.
> 
> BUG=497559, 504121
> 
> Committed: https://crrev.com/29ec87df6cef29b9f28dd21d385f16ce99df9ce3
> Cr-Commit-Position: refs/heads/master@{#336495}

TBR=piman@chromium.org,reveman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=497559, 504121

[grt (UTC plus 2), 2015-06-29 13:52:46]

Created Revert of content: Fix single process support for native
GpuMemoryBuffers.

[commit-bot: I haz the power, 2015-06-29 13:52:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1217853002/1

[commit-bot: I haz the power, 2015-06-29 13:53:28]

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

[commit-bot: I haz the power, 2015-06-29 13:53:30]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-06-29 13:53:49]

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

[reveman, 2015-06-29 15:39:01]

if you can point me to one of the failures I'll try to help determine if this
change is related

[grt (UTC plus 2), 2015-06-29 15:41:51]

On 2015/06/29 15:39:01, reveman wrote:
> if you can point me to one of the failures I'll try to help determine if this
> change is related

I don't think it is related, although someone already reverted this change at
r336531 before me.

The failures are here:
http://build.chromium.org/p/chromium.win/builders/XP%20Tests%20%281%29?numbui....
Let me know if the failures ring any bells.

I filed http://crbug.com/505450 to have troopers take a look, since I believe
the problem may be with the bot or other infrastructure.

Thanks.