Minor GrSurfaceDrawContext retraction

Change-Id: I2378ba6dbce1cf2371eec2dfcf73c3b9378ab832
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/413456
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
6 files changed