YUV to RGB converter

YUV to RGB converter

This is a first piece of the GPU YUV decoder, which is the actual effect that performs the conversion. For now, it simply applies the conversion matrix, since it is all I need. I may add modes if different matrices need to be applied or if I add color profile support here.

I'll try to keep these cls short and easy to review, but there should be a few of them coming once this one is in.

BUG=skia:
R=senorblanco@chromium.org, senorblanco@google.com, reed@google.com, bsalomon@google.com

Author: sugoi@chromium.org

Review URL: https://codereview.chromium.org/378503006