Switch new SkImageFilter internal methods over to sk_sp

src/core/SkLocalMatrixImageFilter.h

 /*
  * Copyright 2015 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 SkLocalMatrixImageFilter_DEFINED
 #define SkLocalMatrixImageFilter_DEFINED
 
 #include "SkImageFilter.h"
 
 /**
  *  Wraps another imagefilter + matrix, such that using this filter will give the same result
  *  as using the wrapped filter with the matrix applied to its context.
  */
 class SkLocalMatrixImageFilter : public SkImageFilter {
 public:
     static SkImageFilter* Create(const SkMatrix& localM, SkImageFilter* input);
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLocalMatrixImageFilter)
 
 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 onFilterBounds(const SkIRect& src, const SkMatrix&, MapDirection) const override;
 
 private:
     SkLocalMatrixImageFilter(const SkMatrix& localM, SkImageFilter* input);
 
     SkMatrix fLocalM;
 
     typedef SkImageFilter INHERITED;
 };
 
 #endif