In DM, use an SkSurface for CPU configs

Some GMs were trying to test for recording backends by calling:

    canvas->getSurface()

... surprisingly, this was returning nullptr on CPU configs, because we
were using the canvas-from-bitmap constructor.

Change-Id: Ic343c3ae9470479911f33cb5c248e261345175f6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/757018
Reviewed-by: John Stiles <johnstiles@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
1 file changed