Remove background obscuration checks.

sky/engine/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple 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
@@ skipping 91 matching lines @@
 
     bool isEnclosedInCompositingLayer() const;
 
     void prepareForDetach();
 
     void clear();
 
     bool isTransparent() const;
     void setTransparent(bool isTransparent);
 
-    // True if the FrameView is not transparent, and the base background color is opaque.
-    bool hasOpaqueBackground() const;
-
     Color baseBackgroundColor() const;
     void setBaseBackgroundColor(const Color&);
     void updateBackgroundRecursively(const Color&, bool);
 
     IntRect windowClipRect(IncludeScrollbarsInRect = ExcludeScrollbars) const;
 
     float visibleContentScaleFactor() const { return m_visibleContentScaleFactor; }
     void setVisibleContentScaleFactor(float);
 
     float inputEventsScaleFactor() const;
@@ skipping 145 matching lines @@
     bool m_layoutSizeFixedToFrameSize;
 
     Vector<IntRect> m_tickmarks;
 };
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_FRAME_FRAMEVIEW_H_