Switch new SkImageFilter internal methods over to sk_sp

include/effects/SkComposeImageFilter.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkComposeImageFilter_DEFINED
 #define SkComposeImageFilter_DEFINED
 
@@ skipping 14 matching lines @@
     SkRect computeFastBounds(const SkRect& src) const override;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkComposeImageFilter)
 
 protected:
     explicit SkComposeImageFilter(SkImageFilter* inputs[2]) : INHERITED(2, inputs) {
         SkASSERT(inputs[0]);
         SkASSERT(inputs[1]);
     }
-    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&, const SkMatrix&, MapDirection) const override;
 
 private:
     typedef SkImageFilter INHERITED;
 };
 
 #endif