templatize GrSurfaceProxyRef

Change-Id: I23e848d852a0c126a6581d2682af3f9e927e876f
Reviewed-on: https://skia-review.googlesource.com/144607
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
11 files changed