Alter SkXfermode's asFragmentProcessor & asXPFactory contracts

include/effects/SkXfermodeImageFilter.h

 /*
  * Copyright 2013 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 SkXfermodeImageFilter_DEFINED
 #define SkXfermodeImageFilter_DEFINED
 
 #include "SkImageFilter.h"
 
 class SkBitmap;
 class SkXfermode;
 
 class SK_API SkXfermodeImageFilter : public SkImageFilter {
     /**
      * This filter takes an xfermode, and uses it to composite the foreground
      * over the background.  If foreground or background is NULL, the input
      * bitmap (src) is used instead.
       */
 
 public:
-    virtual ~SkXfermodeImageFilter();
-
     static SkImageFilter* Create(SkXfermode* mode, SkImageFilter* background,
                                  SkImageFilter* foreground = NULL,
                                  const CropRect* cropRect = NULL) {
         SkImageFilter* inputs[2] = { background, foreground };
         return new SkXfermodeImageFilter(mode, inputs, cropRect);
     }
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkXfermodeImageFilter)
 
     bool onFilterImage(Proxy* proxy,
                        const SkBitmap& src,
                        const Context& ctx,
                        SkBitmap* dst,
                        SkIPoint* offset) const override;
 #if SK_SUPPORT_GPU
     bool canFilterImageGPU() const override;
     bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const Context& ctx,
                         SkBitmap* result, SkIPoint* offset) const override;
 #endif
 
 protected:
     SkXfermodeImageFilter(SkXfermode* mode, SkImageFilter* inputs[2],
                           const CropRect* cropRect);
     void flatten(SkWriteBuffer&) const override;
 
 private:
-    SkXfermode* fMode;
+    SkAutoTUnref<SkXfermode> fMode;
     typedef SkImageFilter INHERITED;
 };
 
 #endif