SkImage now has makeShader to return sk_sp

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1785473002

Review URL: https://codereview.chromium.org/1785473002
diff --git a/gm/image_shader.cpp b/gm/image_shader.cpp
index 084bb95..7ea0202 100644
--- a/gm/image_shader.cpp
+++ b/gm/image_shader.cpp
@@ -101,10 +101,9 @@
 
         const SkShader::TileMode tile = SkShader::kRepeat_TileMode;
         const SkMatrix localM = SkMatrix::MakeTrans(-50, -50);
-        SkAutoTUnref<SkShader> shader(image->newShader(tile, tile, &localM));
         SkPaint paint;
+        paint.setShader(image->makeShader(tile, tile, &localM));
         paint.setAntiAlias(true);
-        paint.setShader(shader);
         canvas->drawCircle(50, 50, 50, paint);
     }