SkPDF: use sk_make_sp<T> when it makes sense.

src/pdf/SkPDFTypes.h

Index: src/pdf/SkPDFTypes.h
diff --git a/src/pdf/SkPDFTypes.h b/src/pdf/SkPDFTypes.h
index 5a48019fd354ddf57f31bc6cb0c16c97600b981a..a6a3e12ee65122f24c15f4e0b87e2726db0276bd 100644
--- a/src/pdf/SkPDFTypes.h
+++ b/src/pdf/SkPDFTypes.h
@@ -109,7 +109,7 @@ public:
     static SkPDFUnion String(const SkString&);
 
     /** This function DOES take ownership of the object. E.g.
-          sk_sp<SkPDFDict> dict(new SkPDFDict);
+          auto dict = sk_make_sp<SkPDFDict>();
           dict->insert(.....);
           SkPDFUnion u = SkPDFUnion::Object(dict.detach()) */
     static SkPDFUnion Object(SkPDFObject*);