Revert "Remove GrSurface::desc() method."

Revert "Remove GrSurface::desc() method."

This reverts commit 9ac995354428a916df81253e0c0c3f582db18976.

Reason for revert: Lots of broken gold images

Original change's description:
> Remove GrSurface::desc() method.
>
> Change-Id: If158dee90b3b0f80aa9c674180fbe6abd5b27d3f
> Reviewed-on: https://skia-review.googlesource.com/17268
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>
>

TBR=bsalomon@google.com,robertphillips@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I5608c0e287e301aeac81dd3249a5c34d4603fcc6
Reviewed-on: https://skia-review.googlesource.com/17306
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>