Revert of move program descriptor generation to flush (patchset #7 id:120001 of https...

Revert of move program descriptor generation to flush (patchset #7 id:120001 of https://codereview.chromium.org/777673003/)

Reason for revert:
breaking linux build

Original issue's description:
> move program descriptor generation to flush
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/829e1b80b1020b17f2078020c990e079b70c077c

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

Review URL: https://codereview.chromium.org/776243005