Consolidate FilterOperation and FilterEffect mapRect implementations

third_party/WebKit/Source/platform/graphics/filters/FEDropShadow.h

 /*
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 13 matching lines @@
 #include "platform/graphics/Color.h"
 #include "platform/graphics/filters/FilterEffect.h"
 
 namespace blink {
 
 class PLATFORM_EXPORT FEDropShadow final : public FilterEffect {
  public:
   static FEDropShadow*
   create(Filter*, float, float, float, float, const Color&, float);
 
+  // Compute which destination area will be affected when applying a drop
+  // shadow effect with |stdDeviation| and |offset| to an area |rect|.
+  static FloatRect mapEffect(const FloatSize& stdDeviation,
+                             const FloatPoint& offset,
+                             const FloatRect&);
+
   void setShadowColor(const Color& color) { m_shadowColor = color; }
   void setShadowOpacity(float opacity) { m_shadowOpacity = opacity; }
 
   TextStream& externalRepresentation(TextStream&, int indention) const override;
 
  private:
   FEDropShadow(Filter*, float, float, float, float, const Color&, float);
 
   FloatRect mapEffect(const FloatRect&) const override;
 
   sk_sp<SkImageFilter> createImageFilter() override;
 
   float m_stdX;
   float m_stdY;
   float m_dx;
   float m_dy;
   Color m_shadowColor;
   float m_shadowOpacity;
 };
 
 }  // namespace blink
 
 #endif  // FEDropShadow_h