SkBlurImageFilter returns input when sigma = 0

gm/imageblur.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkBlurImageFilter.h"
 #include "SkRandom.h"
 
 #define WIDTH 500
 #define HEIGHT 500
 
 void imageblurgm_draw(SkScalar fSigmaX, SkScalar fSigmaY, SkCanvas* canvas) {
         SkPaint paint;
-        paint.setImageFilter(SkBlurImageFilter::Create(fSigmaX, fSigmaY))->unref();
+        SkAutoTUnref<SkImageFilter> blur(SkBlurImageFilter::Create(fSigmaX, fSigmaY));
+        paint.setImageFilter(blur);
         canvas->saveLayer(nullptr, &paint);
         const char* str = "The quick brown fox jumped over the lazy dog.";
 
         SkRandom rand;
         SkPaint textPaint;
         textPaint.setAntiAlias(true);
         sk_tool_utils::set_portable_typeface(&textPaint);
         for (int i = 0; i < 25; ++i) {
             int x = rand.nextULessThan(WIDTH);
             int y = rand.nextULessThan(HEIGHT);
             textPaint.setColor(sk_tool_utils::color_to_565(rand.nextBits(24) | 0xFF000000));
             textPaint.setTextSize(rand.nextRangeScalar(0, 300));
             canvas->drawText(str, strlen(str), SkIntToScalar(x),
                              SkIntToScalar(y), textPaint);
         }
         canvas->restore();
 }
 DEF_SIMPLE_GM_BG(imageblur,       canvas, WIDTH, HEIGHT, SK_ColorBLACK) {
     imageblurgm_draw(24.0f, 0.0f, canvas);
 }
 DEF_SIMPLE_GM_BG(imageblur_large, canvas, WIDTH, HEIGHT, SK_ColorBLACK) {
     imageblurgm_draw(80.0f, 80.0f, canvas);
 }