Enhance SkDropShadowImageFilter to support separate X & Y sigmas, and crop rect.

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"
 
 class SK_API SkDropShadowImageFilter : public SkImageFilter {
 public:
     SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigma, SkColor, SkImageFilter* input = NULL);
+    SkDropShadowImageFilter(SkScalar dx, SkScalar dy, SkScalar sigmaX, SkScalar sigmaY, SkColor, SkImageFilter* input = NULL, const CropRect* cropRect = NULL);

[reed1, 2013/11/26 20:58:39]

At some point we should probably harden up our default arguments, and require
more of them. However, this is not the only case, so lgtm

     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDropShadowImageFilter)
 
 protected:
     explicit SkDropShadowImageFilter(SkFlattenableReadBuffer&);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
     virtual bool onFilterImage(Proxy*, const SkBitmap& source, const SkMatrix&, SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
 
 private:
-    SkScalar fDx, fDy, fSigma;
+    SkScalar fDx, fDy, fSigmaX, fSigmaY;
     SkColor fColor;
     typedef SkImageFilter INHERITED;
 };