Make filters use SkImage instead of SkBitmap

include/effects/SkDropShadowImageFilter.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.
  */
 
 #include "SkColor.h"
 #include "SkImageFilter.h"
 #include "SkScalar.h"
@@ skipping 19 matching lines @@
     }
 
     void computeFastBounds(const SkRect&, SkRect*) const SK_OVERRIDE;
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDropShadowImageFilter)
 
 protected:
     SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigmaX, SkScalar sigmaY, SkColor,
                             ShadowMode shadowMode, SkImageFilter* input, const CropRect* cropRect);
     void flatten(SkWriteBuffer&) const SK_OVERRIDE;
-    bool onFilterImage(Proxy*, const SkBitmap& source, const Context&, SkBitmap* result, SkIPoint* loc) const SK_OVERRIDE;
+    bool onFilterImage(Proxy*, const SkImage* source, const Context&,
+                       SkAutoTUnref<const SkImage>& result,
+                       SkIPoint* loc) const SK_OVERRIDE;
     virtual bool onFilterBounds(const SkIRect& src, const SkMatrix&,
                                 SkIRect* dst) const SK_OVERRIDE;
 
 private:
     SkScalar fDx, fDy, fSigmaX, fSigmaY;
     SkColor fColor;
     ShadowMode fShadowMode;
     typedef SkImageFilter INHERITED;
 };