SkPDF: use sk_ref_sp

src/pdf/SkPDFFormXObject.cpp

Index: src/pdf/SkPDFFormXObject.cpp
diff --git a/src/pdf/SkPDFFormXObject.cpp b/src/pdf/SkPDFFormXObject.cpp
index d565ab81e115664a11813752d63c688f7b8c0726..39d75a5a94e2625acdcca37db5e5d3ac098fee71 100644
--- a/src/pdf/SkPDFFormXObject.cpp
+++ b/src/pdf/SkPDFFormXObject.cpp
@@ -60,8 +60,8 @@ void SkPDFFormXObject::init(const char* colorSpace,
                             SkPDFDict* resourceDict, SkPDFArray* bbox) {
     this->insertName("Type", "XObject");
     this->insertName("Subtype", "Form");
-    this->insertObject("Resources", sk_sp<SkPDFDict>(SkRef(resourceDict)));
-    this->insertObject("BBox", sk_sp<SkPDFArray>(SkRef(bbox)));
+    this->insertObject("Resources", sk_ref_sp(resourceDict));
+    this->insertObject("BBox", sk_ref_sp(bbox));
 
     // Right now SkPDFFormXObject is only used for saveLayer, which implies
     // isolated blending.  Do this conditionally if that changes.