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..d1b82c343d5d59f0c8d1866f3bab750860fdc4cd 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 input;

[Stephen White, 2015/12/10 19:28:40]

One thing I forgot: since the contract is to return a "new" object, we need to
bump the refcount on the input before we return it (this was causing the layout
test failure in Chrome).

Please add:

SkSafeRef(input);

just before this line.

+        }
         return new SkBlurImageFilter(sigmaX, sigmaY, input, cropRect);
     }