Update SkImageSource to sk_sp

bench/MergeBench.cpp

Index: bench/MergeBench.cpp
diff --git a/bench/MergeBench.cpp b/bench/MergeBench.cpp
index 061a4d36f3201478b230d590534168193ad235d3..70b474478404029fe7c2f115fba66f754c0a136c 100644
--- a/bench/MergeBench.cpp
+++ b/bench/MergeBench.cpp
@@ -80,9 +80,8 @@ protected:
 
 private:
     sk_sp<SkImageFilter> mergeBitmaps() {
-        sk_sp<SkImageFilter> first(SkImageSource::Create(fCheckerboard.get()));
-        sk_sp<SkImageFilter> second(SkImageSource::Create(fImage.get()));
-        return SkMergeImageFilter::Make(std::move(first), std::move(second));
+        return SkMergeImageFilter::Make(SkImageSource::Make(fCheckerboard),
+                                        SkImageSource::Make(fImage));
     }
 
     bool fIsSmall;