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

src/pdf/SkPDFFormXObject.cpp

Index: src/pdf/SkPDFFormXObject.cpp
diff --git a/src/pdf/SkPDFFormXObject.cpp b/src/pdf/SkPDFFormXObject.cpp
index 4647f5a8a12b570b947e9dd683d5772a08c8348a..abf331f5444fc10de8e1c9c8ecccc9b483445a56 100644
--- a/src/pdf/SkPDFFormXObject.cpp
+++ b/src/pdf/SkPDFFormXObject.cpp
@@ -65,7 +65,7 @@ void SkPDFFormXObject::init(const char* colorSpace,
 
     // Right now SkPDFFormXObject is only used for saveLayer, which implies
     // isolated blending.  Do this conditionally if that changes.
-    sk_sp<SkPDFDict> group(new SkPDFDict("Group"));
+    auto group = sk_make_sp<SkPDFDict>("Group");
     group->insertName("S", "Transparency");
 
     if (colorSpace != nullptr) {