Add staging for removal of SkRRectsGaussianEdgeShader::Make (for Android)

include/effects/SkRRectsGaussianEdgeShader.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkRRectsGaussianEdgeShader_DEFINED
 #define SkRRectsGaussianEdgeShader_DEFINED
 
 #include "SkShader.h"
 
 class SkRRect;
 
 class SK_API SkRRectsGaussianEdgeShader {
 public:
     /** Returns a shader that applies a Gaussian blur depending on distance to the edge
      *  of the intersection of two round rects.
      *  Currently this is only useable with round rects that have the same radii at
      *  all the corners and for which the x & y radii are equal.
      *  Raster will draw nothing.
      *  
      *  The coverage geometry that should be drawn should be no larger than the intersection
      *  of the bounding boxes of the two round rects. Ambitious users can omit the center
      *  area of the coverage geometry if it is known to be occluded.
      */
     static sk_sp<SkShader> Make(const SkRRect& first,
                                 const SkRRect& second,
-                                SkScalar radius);
+                                SkScalar radius, SkScalar unused = 0.0f);
 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 
 private:
     SkRRectsGaussianEdgeShader(); // can't be instantiated
 };
 
 #endif