SkRectShaderImageFilter: add a new factory method which takes a CropRect.

include/effects/SkRectShaderImageFilter.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.
  */
 
 #ifndef SkRectShaderImageFilter_DEFINED
 #define SkRectShaderImageFilter_DEFINED
 
 #include "SkImageFilter.h"
 #include "SkRect.h"
 
 class SkShader;
 
 class SK_API SkRectShaderImageFilter : public SkImageFilter {
 public:
-    /**
-     *  The SkShader object will have its refcnt increased as it becomes a member of the
-     *  SkRectShaderImageFilter object returned by this function. It cannot be NULL.
-     *  The region parameter is used to specify on which region the shader is applied.
+    /** Create a new image filter which fills the given rectangle with pixels
+     *  produced by the given SkShader. If no rectangle is specified, an output
+     *  is produced with the same bounds as the input primitive (even though 
+     *  the input primitive's pixels are not used for processing).
+     *  @param s     Shader to call for processing. Cannot be NULL. Will be
+     *               ref'ed by the new image filter.
+     *  @param rect  Rectangle of output pixels in which to apply the shader.
+     *               If NULL or a given crop edge is not specified, the source
+     *               primitive's bounds are used instead.
      */
-    static SkRectShaderImageFilter* Create(SkShader* s, const SkRect& rect);
+    /* DEPRECATED */ static SkRectShaderImageFilter* Create(SkShader* s, const SkRect& rect);
+    static SkRectShaderImageFilter* Create(SkShader* s, const CropRect* rect = NULL);
     virtual ~SkRectShaderImageFilter();
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkRectShaderImageFilter)
 
 protected:
     SkRectShaderImageFilter(SkFlattenableReadBuffer& buffer);
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
 
     virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
                                SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
 
 private:
     SkRectShaderImageFilter(SkShader* s, const CropRect* rect);
     SkShader*  fShader;
 
     typedef SkImageFilter INHERITED;
 };
 
 #endif