Add ScrollDirectionPhysical enum in Scroll types.

Source/platform/scroll/Scrollbar.h

 /*
  * Copyright (C) 2004, 2006 Apple Computer, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 146 matching lines @@
     Scrollbar(ScrollableArea*, ScrollbarOrientation, ScrollbarControlSize, ScrollbarTheme* = 0);
 
     void updateThumb();
     virtual void updateThumbPosition();
     virtual void updateThumbProportion();
 
     void autoscrollTimerFired(Timer<Scrollbar>*);
     void startTimerIfNeeded(double delay);
     void stopTimerIfNeeded();
     void autoscrollPressedPart(double delay);
-    ScrollDirection pressedPartScrollDirection();
+    ScrollDirectionPhysical pressedPartScrollDirectionPhysical();
     ScrollGranularity pressedPartScrollGranularity();
 
     ScrollableArea* m_scrollableArea;
     ScrollbarOrientation m_orientation;
     ScrollbarControlSize m_controlSize;
     ScrollbarTheme* m_theme;
 
 #if ENABLE(OILPAN)
     // To simplify Oilpan finalization, keep a copy of the ScrollableArea's
     // scroll animator. Scrollbar is responsible for notifying the animator
@@ skipping 28 matching lines @@
     virtual bool isScrollbar() const override { return true; }
 
     float scrollableAreaCurrentPos() const;
 };
 
 DEFINE_TYPE_CASTS(Scrollbar, Widget, widget, widget->isScrollbar(), widget.isScrollbar());
 
 } // namespace blink
 
 #endif // Scrollbar_h