Remove background obscuration checks.

sky/engine/core/rendering/RenderView.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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 81 matching lines @@
     virtual void updateHitTestResult(HitTestResult&, const LayoutPoint&) override;
 
     IntRect unscaledDocumentRect() const;
     LayoutRect backgroundRect(RenderBox* backgroundRenderer) const;
 
     IntRect documentRect() const;
 
     // Renderer that paints the root background has background-images which all have background-attachment: fixed.
     bool rootBackgroundIsEntirelyFixed() const;
 
-    virtual bool backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const override;
-
     double layoutViewportWidth() const;
     double layoutViewportHeight() const;
 
     void pushLayoutState(LayoutState&);
     void popLayoutState();
 
     void addIFrame(RenderIFrame* iframe);
     void removeIFrame(RenderIFrame* iframe);
     void updateIFramesAfterLayout();
 
@@ skipping 27 matching lines @@
     unsigned m_hitTestCount;
 
     WTF::HashSet<RenderIFrame*> m_iframes;
 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderView, isRenderView());
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_RENDERVIEW_H_