SkPDF: Add sk_sp setters; .release() becomes std::move()

src/pdf/SkPDFGraphicState.cpp

Index: src/pdf/SkPDFGraphicState.cpp
diff --git a/src/pdf/SkPDFGraphicState.cpp b/src/pdf/SkPDFGraphicState.cpp
index 7c4c5e30eb4858f3fc3b4ae0e991aa72b1b013d4..19e9a36d05ca52520787a00e5dfa310b99e22f32 100644
--- a/src/pdf/SkPDFGraphicState.cpp
+++ b/src/pdf/SkPDFGraphicState.cpp
@@ -126,7 +126,7 @@ SkPDFGraphicState* SkPDFGraphicState::GetGraphicStateForPaint(
     return pdfGraphicState;
 }
 
-static SkPDFObject* create_invert_function() {
+static SkPDFStream* create_invert_function() {
     // Acrobat crashes if we use a type 0 function, kpdf crashes if we use
     // a type 2 function, so we use a type 4 function.
     auto domainAndRange = sk_make_sp<SkPDFArray>();
@@ -141,12 +141,17 @@ static SkPDFObject* create_invert_function() {
 
     auto invertFunction = sk_make_sp<SkPDFStream>(psInvertStream.get());
     invertFunction->insertInt("FunctionType", 4);
-    invertFunction->insertObject("Domain", SkRef(domainAndRange.get()));
-    invertFunction->insertObject("Range", domainAndRange.release());
+    invertFunction->insertObject("Domain", domainAndRange);
+    invertFunction->insertObject("Range", std::move(domainAndRange));
     return invertFunction.release();
 }
 
-SK_DECLARE_STATIC_ONCE_PTR(SkPDFObject, invertFunction);
+SK_DECLARE_STATIC_ONCE_PTR(SkPDFStream, invertFunction);
+
+static sk_sp<SkPDFStream> make_invert_function() {
+    return sk_sp<SkPDFStream>(
+            SkRef(invertFunction.get(create_invert_function)));
+}
 
 // static
 SkPDFDict* SkPDFGraphicState::GetSMaskGraphicState(SkPDFFormXObject* sMask,
@@ -160,13 +165,13 @@ SkPDFDict* SkPDFGraphicState::GetSMaskGraphicState(SkPDFFormXObject* sMask,
     } else if (sMaskMode == kLuminosity_SMaskMode) {
         sMaskDict->insertName("S", "Luminosity");
     }
-    sMaskDict->insertObjRef("G", SkRef(sMask));
+    sMaskDict->insertObjRef("G", sk_sp<SkPDFFormXObject>(SkRef(sMask)));
     if (invert) {
-        sMaskDict->insertObjRef("TR", SkRef(invertFunction.get(create_invert_function)));
+        sMaskDict->insertObjRef("TR", make_invert_function());
     }
 
     auto result = sk_make_sp<SkPDFDict>("ExtGState");
-    result->insertObject("SMask", sMaskDict.release());
+    result->insertObject("SMask", std::move(sMaskDict));
     return result.release();
 }