Make converting from 4x4 to 3x3 explicit

Change-Id: I4d190d6831cb517d5e9f22b3f872013367bddc08
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/264856
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/gradients/generated/GrLinearGradientLayout.cpp b/src/gpu/gradients/generated/GrLinearGradientLayout.cpp
index b4da70d..2d5ae3a 100644
--- a/src/gpu/gradients/generated/GrLinearGradientLayout.cpp
+++ b/src/gpu/gradients/generated/GrLinearGradientLayout.cpp
@@ -85,5 +85,5 @@
         return nullptr;
     }
     matrix.postConcat(grad.getGradientMatrix());
-    return std::unique_ptr<GrFragmentProcessor>(new GrLinearGradientLayout(matrix));
+    return std::unique_ptr<GrFragmentProcessor>(new GrLinearGradientLayout(SkMatrix(matrix)));
 }