Switch new SkImageFilter internal methods over to sk_sp

include/effects/SkBlurImageFilter.h

 /*
  * Copyright 2011 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBlurImageFilter_DEFINED
 #define SkBlurImageFilter_DEFINED
 
@@ skipping 10 matching lines @@
         return new SkBlurImageFilter(sigmaX, sigmaY, input, cropRect);
     }
 
     SkRect computeFastBounds(const SkRect&) const override;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBlurImageFilter)
 
 protected:
     void flatten(SkWriteBuffer&) const override;
-    SkSpecialImage* onFilterImage(SkSpecialImage* source, const Context&,
-                                  SkIPoint* offset) const override;
+    sk_sp<SkSpecialImage> onFilterImage(SkSpecialImage* source, const Context&,
+                                        SkIPoint* offset) const override;
     SkIRect onFilterNodeBounds(const SkIRect& src, const SkMatrix&, MapDirection) const override;
 
 private:
     SkBlurImageFilter(SkScalar sigmaX,
                       SkScalar sigmaY,
                       SkImageFilter* input,
                       const CropRect* cropRect);
 
     SkSize   fSigma;
     typedef SkImageFilter INHERITED;
 };
 
 #endif