Fix crash on ImageFilter.blur with very small sigma

display_list/display_list_image_filter.h

@@ -712,7 +712,11 @@ class DlLocalMatrixImageFilter final : public DlImageFilter {
     if (!image_filter_) {
       return nullptr;
     }
-    return image_filter_->skia_object()->makeWithLocalMatrix(matrix_);
+    sk_sp<SkImageFilter> skia_object = image_filter_->skia_object();
+    if (!skia_object) {
+      return nullptr;
+    }
+    return skia_object->makeWithLocalMatrix(matrix_);
   }
 
  protected:

display_list/display_list_image_filter_unittests.cc

@@ -846,6 +846,16 @@ TEST(DisplayListImageFilter, LocalImageFilterBounds) {
   }
 }
 
+TEST(DisplayListImageFilter, LocalImageSkiaNull) {
+  auto blur_filter =
+      std::make_shared<DlBlurImageFilter>(0, 0, DlTileMode::kClamp);
+  DlLocalMatrixImageFilter dl_local_matrix_filter(SkMatrix::RotateDeg(45),
+                                                  blur_filter);
+  // With sigmas set to zero on the blur filter, Skia will return a null filter.
+  // The local matrix filter should return nullptr instead of crashing.
+  ASSERT_EQ(dl_local_matrix_filter.skia_object(), nullptr);
+}
+
 TEST(DisplayListImageFilter, UnknownEquals) {
   sk_sp<SkImageFilter> sk_filter =
       SkImageFilters::Blur(5.0, 6.0, SkTileMode::kRepeat, nullptr);