Revert of Refactor Vaapi video decoder/encoder in preparation of Freon support

Revert of Refactor Vaapi video decoder/encoder in preparation of Freon support (patchset #6 id:100001 of https://codereview.chromium.org/807853005/)

Reason for revert:
Caused build failure on Linux ChromiumOS GN:
ninja: error: '../../content/common/content/common/gpu/media/va_x11.sigs',
needed by 'obj/content/common/libva_generate_stubs.inputdeps.stamp', missing
and no known rule to make it

Original issue's description:
> Refactor Vaapi video decoder/encoder in preparation of Freon support
>
> This introduces VaapiPicture which abstracts the output picture for the VaapiVideoDecodeAccelerator.
> This also splits out the x11 specific functions of LibVA into their own signature file.
> And finally this adds back GLImageGLX to match the code path that will be used on Freon, using GLImageLinuxDMABuffer.
>
> BUG=403058
> TEST=video_decode_accelerator_unittest and video_encode_accelerator_unittest
>
> Committed: https://crrev.com/289e96375e75be0d9158b86df2bd4faf2d7b2a64
> Cr-Commit-Position: refs/heads/master@{#309355}

TBR=reveman@chromium.org,posciak@chromium.org,scherkus@chromium.org,piman@chromium.org,lionel.g.landwerlin@intel.com
NOTREECHECKS=true
NOTRY=true
BUG=403058
Committed: https://crrev.com/6dc14e495d4ca089c096ba0263fd5269647de838
Cr-Commit-Position: refs/heads/master@{#309356}

[dcheng, 2014-12-20 18:49:44]

Created Revert of Refactor Vaapi video decoder/encoder in preparation of Freon
support

[commit-bot: I haz the power, 2014-12-20 18:50:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/804353003/1

[commit-bot: I haz the power, 2014-12-20 18:51:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-20 18:52:15]

Patchset 1 (id:??) landed as
https://crrev.com/6dc14e495d4ca089c096ba0263fd5269647de838
Cr-Commit-Position: refs/heads/master@{#309356}