Underline Thickness is not uniform

Source/core/rendering/RootInlineBox.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008 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
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 96 matching lines @@
     void paintEllipsisBox(PaintInfo&, const LayoutPoint&, LayoutUnit lineTop, LayoutUnit lineBottom) const;
 
     virtual void clearTruncation() OVERRIDE FINAL;
 
     bool isHyphenated() const;
 
     virtual int baselinePosition(FontBaseline baselineType) const OVERRIDE FINAL;
     virtual LayoutUnit lineHeight() const OVERRIDE FINAL;
 
     virtual void paint(PaintInfo&, const LayoutPoint&, LayoutUnit lineTop, LayoutUnit lineBottom) OVERRIDE;
+    virtual void paintDecorationStyle(PaintInfo&, const LayoutPoint&, LayoutUnit lineTop, LayoutUnit lineBottom, float decorationThickness) OVERRIDE;
+    virtual void getPaintDecorationSyle(PaintInfo&, const LayoutPoint& , float *) OVERRIDE;
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, LayoutUnit lineTop, LayoutUnit lineBottom) OVERRIDE FINAL;
 
     using InlineBox::hasSelectedChildren;
     using InlineBox::setHasSelectedChildren;
 
     virtual RenderObject::SelectionState selectionState() OVERRIDE FINAL;
     InlineBox* firstSelectedBox();
     InlineBox* lastSelectedBox();
 
     GapRects lineSelectionGap(RenderBlock* rootBlock, const LayoutPoint& rootBlockPhysicalPosition, const LayoutSize& offsetFromRootBlock, LayoutUnit selTop, LayoutUnit selHeight, const PaintInfo*);
@@ skipping 105 matching lines @@
     OwnPtr<LineFragmentationData> m_fragmentationData;
 
     // Floats hanging off the line are pushed into this vector during layout. It is only
     // good for as long as the line has not been marked dirty.
     OwnPtr<Vector<RenderBox*> > m_floats;
 };
 
 } // namespace WebCore
 
 #endif // RootInlineBox_h