Re-arrange GrResourceProvider's texture creation methods

This is all in service of removing the last raw writeSurfacePixels (that we can do anything about)

Change-Id: Ic84f677b2440b20e5fcc23e787584db0cfaecd01
Reviewed-on: https://skia-review.googlesource.com/13584
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
4 files changed