Factor out the <textPath> positioning mapping code into a helper class

third_party/WebKit/Source/core/layout/api/LineLayoutSVGTextPath.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef LineLayoutSVGTextPath_h
 #define LineLayoutSVGTextPath_h
 
 #include "core/layout/api/LineLayoutSVGInline.h"
 #include "core/layout/svg/LayoutSVGTextPath.h"
 
 namespace blink {
 
 class LineLayoutSVGTextPath : public LineLayoutSVGInline {
 public:
     explicit LineLayoutSVGTextPath(LayoutSVGTextPath* layoutSVGTextPath)
         : LineLayoutSVGInline(layoutSVGTextPath)
     {
     }
 
     explicit LineLayoutSVGTextPath(const LineLayoutItem& item)
         : LineLayoutSVGInline(item)
     {
         ASSERT(!item || item.isSVGTextPath());
     }
 
     explicit LineLayoutSVGTextPath(std::nullptr_t) : LineLayoutSVGInline(nullptr) { }
 
     LineLayoutSVGTextPath() { }
 
-    Path layoutPath() const
+    PassOwnPtr<PathPositionMapper> layoutPath() const
     {
         return toSVGTextPath()->layoutPath();
     }
 
     float calculateStartOffset(float pathLength) const
     {
         return toSVGTextPath()->calculateStartOffset(pathLength);
     }
 
 private:
     LayoutSVGTextPath* toSVGTextPath()
     {
         return toLayoutSVGTextPath(layoutObject());
     }
 
     const LayoutSVGTextPath* toSVGTextPath() const
     {
         return toLayoutSVGTextPath(layoutObject());
     }
 };
 
 } // namespace blink
 
 #endif // LineLayoutSVGTextPath_h