Implement Middle Click Autoscroll on all platforms not just Windows

third_party/WebKit/Source/core/layout/LayoutBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 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.
  *
@@ skipping 751 matching lines @@
     int scrollbarLogicalWidth() const { return style()->isHorizontalWritingMode() ? verticalScrollbarWidth() : horizontalScrollbarHeight(); }
     int scrollbarLogicalHeight() const { return style()->isHorizontalWritingMode() ? horizontalScrollbarHeight() : verticalScrollbarWidth(); }
     virtual ScrollResult scroll(ScrollGranularity, const FloatSize&);
     bool canBeScrolledAndHasScrollableArea() const;
     virtual bool canBeProgramaticallyScrolled() const;
     virtual void autoscroll(const IntPoint&);
     bool canAutoscroll() const;
     IntSize calculateAutoscrollDirection(const IntPoint& pointInRootFrame) const;
     static LayoutBox* findAutoscrollable(LayoutObject*);
     virtual void stopAutoscroll() { }
-    virtual void panScroll(const IntPoint&);
+    virtual void middleClickAutoscroll(const IntPoint&);
 
     DISABLE_CFI_PERF bool hasAutoVerticalScrollbar() const { return hasOverflowClip() && (style()->overflowY() == OverflowAuto || style()->overflowY() == OverflowPagedY || style()->overflowY() == OverflowOverlay); }
     DISABLE_CFI_PERF bool hasAutoHorizontalScrollbar() const { return hasOverflowClip() && (style()->overflowX() == OverflowAuto || style()->overflowX() == OverflowOverlay); }
     DISABLE_CFI_PERF bool scrollsOverflow() const { return scrollsOverflowX() || scrollsOverflowY(); }
     virtual bool shouldPlaceBlockDirectionScrollbarOnLogicalLeft() const { return style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft(); }
 
     bool hasScrollableOverflowX() const { return scrollsOverflowX() && pixelSnappedScrollWidth() != pixelSnappedClientWidth(); }
     bool hasScrollableOverflowY() const { return scrollsOverflowY() && pixelSnappedScrollHeight() != pixelSnappedClientHeight(); }
     virtual bool scrollsOverflowX() const { return hasOverflowClip() && (style()->overflowX() == OverflowScroll || hasAutoHorizontalScrollbar()); }
     virtual bool scrollsOverflowY() const { return hasOverflowClip() && (style()->overflowY() == OverflowScroll || hasAutoVerticalScrollbar()); }
@@ skipping 433 matching lines @@
         || breakValue == BreakLeft
         || breakValue == BreakPage
         || breakValue == BreakRecto
         || breakValue == BreakRight
         || breakValue == BreakVerso;
 }
 
 } // namespace blink
 
 #endif // LayoutBox_h