Switch new SkImageFilter internal methods over to sk_sp

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1826893002

Review URL: https://codereview.chromium.org/1826893002
diff --git a/src/effects/SkImageSource.cpp b/src/effects/SkImageSource.cpp
index d63eda9..f095df6 100644
--- a/src/effects/SkImageSource.cpp
+++ b/src/effects/SkImageSource.cpp
@@ -65,8 +65,8 @@
     buffer.writeImage(fImage.get());
 }
 
-SkSpecialImage* SkImageSource::onFilterImage(SkSpecialImage* source, const Context& ctx,
-                                             SkIPoint* offset) const {
+sk_sp<SkSpecialImage> SkImageSource::onFilterImage(SkSpecialImage* source, const Context& ctx,
+                                                   SkIPoint* offset) const {
     SkRect dstRect;
     ctx.ctm().mapRect(&dstRect, fDstRect);
 
@@ -76,7 +76,7 @@
         offset->fX = offset->fY = 0;
         return SkSpecialImage::MakeFromImage(source->internal_getProxy(),
                                              SkIRect::MakeWH(fImage->width(), fImage->height()),
-                                             fImage).release();
+                                             fImage);
     }
 
     const SkIRect dstIRect = dstRect.roundOut();
@@ -110,7 +110,7 @@
 
     offset->fX = dstIRect.fLeft;
     offset->fY = dstIRect.fTop;
-    return surf->makeImageSnapshot().release();
+    return surf->makeImageSnapshot();
 }
 
 SkRect SkImageSource::computeFastBounds(const SkRect& src) const {