Revert of Enable GpuMemoryBuffers video frames on MacOS.

Revert of Enable GpuMemoryBuffers video frames on MacOS. (patchset #1 id:1 of https://codereview.chromium.org/1308913003/ )

Reason for revert:
Suspicious for breaking Mac OS Blink layout tests that play videos.

BUG=524733
Original issue's description:
> Enable GpuMemoryBuffers video frames on MacOS.
>
> This patch enables UYVY GpuMemoryBuffers backed VideoFrames on MacOSX
> for software decoded videos.
> This change allows VideoLayers to be promoted to overlays when possible.
> Power measuraments showed a significant reduction in Watts consumed
> during video playback: in the tests ran by ccameron@ it went from 3.15
> Watts to 2.13 Watts.
>
> Additionally this change avoids one copy of the VideoFrame in the GPU
> process and moves away another copy from the Compositor thread to
> media.
>
> Unfortunately, for videos where the decoding time is close to the frame
> time, the additional copy might slow down the decoding past the limit,
> causing more dropped frames in these cases.
>
> More benchmark results can be found here:
> https://x20web.corp.google.com/~dcastagna/results_all.html
>
> The first run is with GMB video frames disabled, the second one, enabled.
>
> BUG=485859, 510252
>
> Committed: https://crrev.com/96463459619f441a721f96c51c357208604b7475
> Cr-Commit-Position: refs/heads/master@{#345418}

TBR=andresantoso@chromium.org,avi@chromium.org,ccameron@chromium.org,piman@chromium.org,dalecurtis@chromium.org,dcastagna@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=485859, 510252
Committed: https://crrev.com/36a695fef45fe446217df867e3c36ca07d2d5ac3
Cr-Commit-Position: refs/heads/master@{#345482}

[mnaganov (inactive), 2015-08-25 23:30:00]

Created Revert of Enable GpuMemoryBuffers video frames on MacOS.

[commit-bot: I haz the power, 2015-08-25 23:30:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313123008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313123008/1

[commit-bot: I haz the power, 2015-08-25 23:33:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-25 23:34:01]

Patchset 1 (id:??) landed as
https://crrev.com/36a695fef45fe446217df867e3c36ca07d2d5ac3
Cr-Commit-Position: refs/heads/master@{#345482}