The new ops attempt to be less optimal by falling back to CPU conversions
rather than relying on intermediate draws and complex coordination between
GrContext and GrGpu to determine how conversions are performed.
This adds the new writePixels implementation.
Change-Id: I7496d86d5a40277ed2ca63668881c160e54d80d3
Reviewed-on: https://skia-review.googlesource.com/109880
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
5f33a8ccac