Add IORef capability to GrSurfaceProxy objects - take 2

include/gpu/GrGpuResource.h

Index: include/gpu/GrGpuResource.h
diff --git a/include/gpu/GrGpuResource.h b/include/gpu/GrGpuResource.h
index 4597464f02d5b6725fa5820bff0a3eed66d99c16..29d33df4bdb824e0f982d3db038ea1d58b75a701 100644
--- a/include/gpu/GrGpuResource.h
+++ b/include/gpu/GrGpuResource.h
@@ -93,6 +93,8 @@ protected:
     bool internalHasRef() const { return SkToBool(fRefCnt); }
 
 private:
+    friend class GrIORefProxy; // needs to forward on wrapped IO calls
+
     void addPendingRead() const {
         this->validate();
         ++fPendingReads;