Make GrPipeline hold a GrRenderTargetProxy (instead of a GrRenderTarget)

In a future world where GrSurface no longer has an origin it will be
useful for the GrPipeline to be holding the GrRenderTargetProxy (which will
still have an origin).

Change-Id: I743a8cc07b6b92f8116227fb77b7c37da43cde8a
Reviewed-on: https://skia-review.googlesource.com/26804
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/ccpr/GrCoverageCountingPathRenderer.cpp b/src/gpu/ccpr/GrCoverageCountingPathRenderer.cpp
index 45fad1f..5a9afa1 100644
--- a/src/gpu/ccpr/GrCoverageCountingPathRenderer.cpp
+++ b/src/gpu/ccpr/GrCoverageCountingPathRenderer.cpp
@@ -298,7 +298,7 @@
     args.fCaps = &flushState->caps();
     args.fProcessors = &fProcessors;
     args.fFlags = fSRGBFlags;
-    args.fRenderTarget = flushState->drawOpArgs().fRenderTarget;
+    args.fProxy = flushState->drawOpArgs().fProxy;
     args.fDstProxy = flushState->drawOpArgs().fDstProxy;
     pipeline.init(args);