Make op-level texture uploading be GrProxy-based

Change-Id: I898d626eff059fa7c687357b536d09409a174358
Reviewed-on: https://skia-review.googlesource.com/28001
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ops/GrDrawOp.h b/src/gpu/ops/GrDrawOp.h
index 58ef71a..54b9f16 100644
--- a/src/gpu/ops/GrDrawOp.h
+++ b/src/gpu/ops/GrDrawOp.h
@@ -47,7 +47,7 @@
 class GrDrawOp : public GrOp {
 public:
     /** Method that performs an upload on behalf of a DeferredUploadFn. */
-    using WritePixelsFn = std::function<bool(GrSurface* texture,
+    using WritePixelsFn = std::function<bool(GrTextureProxy*,
                                              int left, int top, int width, int height,
                                              GrPixelConfig config, const void* buffer,
                                              size_t rowBytes)>;