SkBlurImageFilter returns input when sigma = 0

include/effects/SkBlurImageFilter.h

Index: include/effects/SkBlurImageFilter.h
diff --git a/include/effects/SkBlurImageFilter.h b/include/effects/SkBlurImageFilter.h
index 7f62634a9eb9b6d58bcc2c72c85d5dae2c2bc527..5ae013d78e789878f0645277faa06e885d1e7fb1 100644
--- a/include/effects/SkBlurImageFilter.h
+++ b/include/effects/SkBlurImageFilter.h
@@ -15,6 +15,9 @@ class SK_API SkBlurImageFilter : public SkImageFilter {
 public:
     static SkImageFilter* Create(SkScalar sigmaX, SkScalar sigmaY, SkImageFilter* input = NULL,
                                  const CropRect* cropRect = NULL) {
+        if (0 == sigmaX && 0 == sigmaY && nullptr == cropRect) {
+            return SkSafeRef(input);
+        }
         return new SkBlurImageFilter(sigmaX, sigmaY, input, cropRect);
     }