Remove GrRefCnt.h in favor of SkRefCnt.h

include/core/SkRefCnt.h

Index: include/core/SkRefCnt.h
diff --git a/include/core/SkRefCnt.h b/include/core/SkRefCnt.h
index 87ff7dba9fcd338b424ba404f7abab2632ab4fb4..35f7349778035c4071cacd4979c85c5066e1ddbc 100644
--- a/include/core/SkRefCnt.h
+++ b/include/core/SkRefCnt.h
@@ -160,6 +160,13 @@ template <typename T> static inline void SkSafeUnref(T* obj) {
     }
 }
 
+template<typename T> static inline void SkSafeSetNull(T*& obj) {
+    if (NULL != obj) {
+        obj->unref();
+        obj = NULL;
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 /**