Make filters use SkImage instead of SkBitmap

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 SkXfermodeImageFilter* Create(SkXfermode* mode, SkImageFilter* background,
                                          SkImageFilter* foreground = NULL,
                                          const CropRect* cropRect = NULL) {
         SkImageFilter* inputs[2] = { background, foreground };
         return SkNEW_ARGS(SkXfermodeImageFilter, (mode, inputs, cropRect));
     }
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkXfermodeImageFilter)
 
     virtual bool onFilterImage(Proxy* proxy,
-                               const SkBitmap& src,
+                               const SkImage* src,
                                const Context& ctx,
-                               SkBitmap* dst,
+                               SkAutoTUnref<const SkImage>& dst,
                                SkIPoint* offset) const SK_OVERRIDE;
 #if SK_SUPPORT_GPU
     bool canFilterImageGPU() const SK_OVERRIDE;
-    virtual bool filterImageGPU(Proxy* proxy, const SkBitmap& src, const Context& ctx,
-                                SkBitmap* result, SkIPoint* offset) const SK_OVERRIDE;
+    virtual bool filterImageGPU(Proxy* proxy, const SkImage* src, const Context& ctx,
+                                SkAutoTUnref<const SkImage>& result, SkIPoint* offset) const SK_OVERRIDE;
 #endif
 
 protected:
     SkXfermodeImageFilter(SkXfermode* mode, SkImageFilter* inputs[2],
                           const CropRect* cropRect);
     void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
 private:
     SkXfermode* fMode;
     typedef SkImageFilter INHERITED;
 };
 
 #endif