Update MatrixConvolutionImageFilter to sk_sp

TBR=reed@google.com

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1869833002

Review URL: https://codereview.chromium.org/1869833002
diff --git a/samplecode/SampleFilterFuzz.cpp b/samplecode/SampleFilterFuzz.cpp
index a7f4163..f09c6a5 100644
--- a/samplecode/SampleFilterFuzz.cpp
+++ b/samplecode/SampleFilterFuzz.cpp
@@ -555,7 +555,7 @@
         filter = SkAlphaThresholdFilter::Make(make_region(),
                                               make_scalar(),
                                               make_scalar(),
-                                              nullptr);
+                                              make_image_filter());
         break;
     case MERGE:
         filter = SkMergeImageFilter::Make(make_image_filter(),
@@ -614,18 +614,16 @@
         }
         SkIPoint kernelOffset = SkIPoint::Make(R(SkIntToScalar(size.width())),
                                                R(SkIntToScalar(size.height())));
-        sk_sp<SkImageFilter> subFilter(make_image_filter());
 
-        filter = sk_sp<SkImageFilter>(SkMatrixConvolutionImageFilter::Create(
-                                                        size,
-                                                        kernel.begin(),
-                                                        make_scalar(),
-                                                        make_scalar(),
-                                                        kernelOffset,
-                                                        (SkMatrixConvolutionImageFilter::TileMode)R(3),
-                                                        R(2) == 1,
-                                                        subFilter.get(),
-                                                        &cropR));
+        filter = SkMatrixConvolutionImageFilter::Make(size,
+                                                      kernel.begin(),
+                                                      make_scalar(),
+                                                      make_scalar(),
+                                                      kernelOffset,
+                                                      (SkMatrixConvolutionImageFilter::TileMode)R(3),
+                                                      R(2) == 1,
+                                                      make_image_filter(),
+                                                      &cropR);
         break;
     }
     case COMPOSE: