Add method to GrProgramResource to record that pending a execution was completed.

include/gpu/GrGpuResource.h

Index: include/gpu/GrGpuResource.h
diff --git a/include/gpu/GrGpuResource.h b/include/gpu/GrGpuResource.h
index 189237a9441733f05a90e531cf628bf8e121c0ea..d117c42533e1841a0a8a737311749ff8ccd21671 100644
--- a/include/gpu/GrGpuResource.h
+++ b/include/gpu/GrGpuResource.h
@@ -109,8 +109,7 @@ private:
     mutable int32_t fPendingReads;
     mutable int32_t fPendingWrites;
 
-    // These functions need access to the pending read/write member functions.
-    friend class GrRODrawState;
+    // This class is used to manage conversion of refs to pending reads/writes.
     friend class GrProgramResource;
 };