SkBlurImageFilter returns input when sigma = 0

gm/imagefilters.cpp

Index: gm/imagefilters.cpp
diff --git a/gm/imagefilters.cpp b/gm/imagefilters.cpp
index af2c776ce186e77d8e72b6bb4a0d9d81d984da5e..ff8a69054acfe7b385b60b406fe5cd436e5b365b 100644
--- a/gm/imagefilters.cpp
+++ b/gm/imagefilters.cpp
@@ -87,7 +87,8 @@ DEF_SIMPLE_GM(fast_slow_blurimagefilter, canvas, 620, 260) {
     canvas->translate(10, 10);
     for (SkScalar sigma = 8; sigma <= 128; sigma *= 2) {
         SkPaint paint;
-        paint.setImageFilter(SkBlurImageFilter::Create(sigma, sigma))->unref();
+        SkAutoTUnref<SkImageFilter> blur(SkBlurImageFilter::Create(sigma, sigma));
+        paint.setImageFilter(blur.get());
 
         canvas->save();
         // we outset the clip by 1, to fall out of the fast-case in drawImage