Revert of Mac Video Capture AVFoundation: Calculate compressed frame size for MJPEG.

Revert of Mac Video Capture AVFoundation: Calculate compressed frame size for MJPEG. (patchset #2 id:20001 of https://codereview.chromium.org/912293005/)

Reason for revert:
An improved version of ValidateJpeg in libyuv has been rolled into chromium and this CL is no longer needed.

Original issue's description:
> Mac Video Capture AVFoundation: Calculate compressed frame size for MJPEG.
>
> The frame size we receive from AVFoundation is sometimes excessive, e.g. the size of the uncompressed frame. For example, for a JPEG YUV422, the reported size might be 1280*720*2 = 1.8MB, while the actual compressed data is only 260kB.
>
> In these cases, libyuv::MJPGToI420 spends a lot of time in libyuv::ValidateJpeg, as much as 25%. The reason for this is that ValidateJpeg starts at the end of the buffer and loops backwards looking for the End Of Image (EOI) marker.
>
> This CL tries to optimize these cases by finding the EOI by looping forwards instead of backwards, and reporting the actual frame size to libyuv::MJPGToI420.
>
> BUG=346634, 460497
>
> Committed: https://crrev.com/dc556d2b54354adc95ee5474600f469f7ae65692
> Cr-Commit-Position: refs/heads/master@{#317333}

TBR=perkj@chromium.org,mcasas@chromium.org,tommi@chromium.org,torbjorng@google.com,torbjorng@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=346634, 460497
Committed: https://crrev.com/0deddb9627adb0a4d473c6e0fdafa8e32062101e
Cr-Commit-Position: refs/heads/master@{#325211}

[magjed_chromium, 2015-04-15 08:30:17]

Created Revert of Mac Video Capture AVFoundation: Calculate compressed frame
size for MJPEG.

[magjed_chromium, 2015-04-15 08:31:19]

The CQ bit was checked by magjed@chromium.org

[commit-bot: I haz the power, 2015-04-15 08:32:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1089173003/1

[commit-bot: I haz the power, 2015-04-15 08:33:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-15 08:34:48]

Patchset 1 (id:??) landed as
https://crrev.com/0deddb9627adb0a4d473c6e0fdafa8e32062101e
Cr-Commit-Position: refs/heads/master@{#325211}