Move WebVTT snap-to-lines layout code to a helper class

Source/core/rendering/RenderVTTCue.h

Index: Source/core/rendering/RenderVTTCue.h
diff --git a/Source/core/rendering/RenderVTTCue.h b/Source/core/rendering/RenderVTTCue.h
index 5683da6d22f9722273ee4e90b7507b176fe35ce8..112a10259ac4ed79dda695bea611c5467a1f0c85 100644
--- a/Source/core/rendering/RenderVTTCue.h
+++ b/Source/core/rendering/RenderVTTCue.h
@@ -42,21 +42,10 @@ public:
 private:
     virtual void layout() override;
 
-    bool isOutside() const;
-    bool isOverlapping() const;
-    bool shouldSwitchDirection(InlineFlowBox*, LayoutUnit) const;
-
-    void moveBoxesByStep(LayoutUnit);
-    bool switchDirection(bool&, LayoutUnit&);
-
-    bool findFirstLineBox(InlineFlowBox*&);
-    bool initializeLayoutParameters(InlineFlowBox*, LayoutUnit&, LayoutUnit&);
-    void placeBoxInDefaultPosition(LayoutUnit, bool&);
-    void repositionCueSnapToLinesSet();
+    void adjustForTopAndBottomMarginBorderAndPadding();
     void repositionCueSnapToLinesNotSet();
 
     RawPtrWillBeMember<VTTCue> m_cue;
-    LayoutPoint m_specifiedPosition;
 };
 
 } // namespace blink