Switch SkMergeImageFilter over to new onFilterImage interface

include/effects/SkMergeImageFilter.h

 /*
  * Copyright 2012 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 SkMergeImageFilter_DEFINED
 #define SkMergeImageFilter_DEFINED
 
 #include "SkImageFilter.h"
 
 #include "SkXfermode.h"
 
 class SK_API SkMergeImageFilter : public SkImageFilter {
 public:
-    virtual ~SkMergeImageFilter();
+    ~SkMergeImageFilter() override;
 
     static SkImageFilter* Create(SkImageFilter* first, SkImageFilter* second,
                                  SkXfermode::Mode mode = SkXfermode::kSrcOver_Mode,
                                  const CropRect* cropRect = NULL) {
         SkImageFilter* inputs[2] = { first, second };
         SkXfermode::Mode modes[2] = { mode, mode };
         return new SkMergeImageFilter(inputs, 2, modes, cropRect);
     }
 
     static SkImageFilter* Create(SkImageFilter* filters[], int count,
                                  const SkXfermode::Mode modes[] = NULL,
                                 const CropRect* cropRect = NULL) {
         return new SkMergeImageFilter(filters, count, modes, cropRect);
     }
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMergeImageFilter)
 
 protected:
     void flatten(SkWriteBuffer&) const override;
-    bool onFilterImageDeprecated(Proxy*, const SkBitmap& src, const Context&, SkBitmap* result,
-                                 SkIPoint* loc) const override;
+    SkSpecialImage* onFilterImage(SkSpecialImage* source, const Context&,
+                                  SkIPoint* offset) const override;
 
 private:
     SkMergeImageFilter(SkImageFilter* filters[], int count, const SkXfermode::Mode modes[],
                        const CropRect* cropRect);
 
     uint8_t*    fModes; // SkXfermode::Mode
 
     // private storage, to avoid dynamically allocating storage for our copy
     // of the modes (unless the count is so large we can't fit).
     intptr_t    fStorage[16];
 
     void initAllocModes();
     void initModes(const SkXfermode::Mode []);
 
     typedef SkImageFilter INHERITED;
 };
 
 #endif