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

include/effects/SkRectShaderImageFilter.h

Index: include/effects/SkRectShaderImageFilter.h
diff --git a/include/effects/SkRectShaderImageFilter.h b/include/effects/SkRectShaderImageFilter.h
index 5ad11c104c72b837a877014ccbca183a432b7159..f7d4a03d8b49b6084beab6763bc2f059ffa2c563 100644
--- a/include/effects/SkRectShaderImageFilter.h
+++ b/include/effects/SkRectShaderImageFilter.h
@@ -21,6 +21,7 @@ public:
      *  The region parameter is used to specify on which region the shader is applied.

[reed1, 2013/10/14 12:45:57]

1. "region"?
2. It appears now that the rect/region is optional. Can you update the dox to
clarify what happens in that case?
3. Can you document what this filter does? e.g. why are we passing in a shader?

      */
     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)