Expand tap highlight to allow multiple highlights for touch disambiguation.

Source/web/LinkHighlight.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 124 matching lines @@
             newGraphicsLayer = renderLayer->backing()->scrollingContentsLayer();
         } else
             ASSERT_NOT_REACHED();
     }
 
     if (m_currentGraphicsLayer != newGraphicsLayer) {
         if (m_currentGraphicsLayer)
             clearGraphicsLayerLinkHighlightPointer();
 
         m_currentGraphicsLayer = newGraphicsLayer;
-        m_currentGraphicsLayer->setLinkHighlight(this);
+        m_currentGraphicsLayer->addLinkHighlight(this);
     }
 
     return renderLayer;
 }
 
 static void convertTargetSpaceQuadToCompositedLayer(const FloatQuad& targetSpaceQuad, RenderObject* targetRenderer, RenderObject* compositedRenderer, FloatQuad& compositedSpaceQuad)
 {
     ASSERT(targetRenderer);
     ASSERT(compositedRenderer);
 
@@ skipping 120 matching lines @@
     m_contentLayer->layer()->setDrawsContent(true);
     m_contentLayer->layer()->addAnimation(m_animation.get());
 
     invalidate();
     m_owningWebViewImpl->scheduleAnimation();
 }
 
 void LinkHighlight::clearGraphicsLayerLinkHighlightPointer()
 {
     if (m_currentGraphicsLayer) {
-        m_currentGraphicsLayer->setLinkHighlight(0);
+        m_currentGraphicsLayer->removeLinkHighlight(this);
         m_currentGraphicsLayer = 0;
     }
 }
 
 void LinkHighlight::notifyAnimationStarted(double)
 {
 }
 
 void LinkHighlight::notifyAnimationFinished(double)
 {
@@ skipping 37 matching lines @@
     // Make sure we update geometry on the next callback from WebViewImpl::layout().
     m_geometryNeedsUpdate = true;
 }
 
 WebLayer* LinkHighlight::layer()
 {
     return clipLayer();
 }
 
 } // namespace WeKit