Restore offscreen surface example, Add GPU/CPU reporting function.

Change-Id: Ic360cef53aa22983e8b17a3488e97d6f28b27d97
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/288894
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Nathaniel Nifong <nifong@google.com>
3 files changed