Revert of Create xfer processor backend. (patchset #6 id:100001 of https://codereview.chromium.org/764643004/)

Reason for revert:
CL breaks windows DM

Original issue's description:
> Create xfer processor backend.
>
> This includes:
> -Having an actual XP stage at the end of the gl pipeline.
> -All Blending work is handled by XP until actually setting GL blend states
> -GLPrograms test to test XP
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/4dffc940c430eec66d4707490eace19c9b3f7904

TBR=bsalomon@google.com,joshualitt@chromium.org,egdaniel@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/789343002
22 files changed