Revert 177842. This doesn't build in standalone webkit builds:

Revert 177842. This doesn't build in standalone webkit builds:
https://bugs.webkit.org/show_bug.cgi?id=107468

It looks like the exact same problem happened when this landed the last time:
https://bugs.webkit.org/show_bug.cgi?id=105813

Please make sure this issue is fixed before you reland.

The CL also likely regressed binary size by 0.25MB: http://crbug.com/171143

> Add wrapper class to media for support of VP9 video, and add a command line flag to enable the support.
> 
> This initial version of the wrapper provides support for decoding VP9 video in WebM container files, and is disabled by default.
> 
> New flag added: --enable-vp9-playback
> 
> TBR=brettw,scherkus,xhwang
> BUG=166094
> TEST=VP9 video in WebM containers plays back in <video> elements when --enable-vp9-playback is specified on the command line.
> 
> 
> Review URL: https://chromiumcodereview.appspot.com/12025030

TBR=tomfinegan@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=177953