Revert 113895 - <video> decode in hardware!

Revert 113895 - <video> decode in hardware!

This uses the GpuVideoDecodeAccelerator machinery (already written to enable
ppapi to take advantage of OpenMAX HW where available) to decode <video> data.
This increases idle CPU from 20% to 45% on one particularly large (internal)
test video (red0.mp4), on an ARM crosbook.

HW decode is done on a best-effort basis; if the GPU code doesn't know how to
deal with a codec/profile we still fall back to ffmpeg for decode.  Because the
vast majority of chrome installs will be on HW with no video decode support
(yet) we only attempt HW video decode on platforms we know have a shot at it.

BUG=104579
TEST=manual testing w/ video test matrix, trybots.

Review URL: http://codereview.chromium.org/8686010

TBR=fischman@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=113908