Expose scroll customization for touch to JS (behind REF).

Source/core/testing/Internals.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple 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.
@@ skipping 319 matching lines @@
     PassRefPtrWillBeRawPtr<ClientRectList> getTransitionElementRects();
     void hideAllTransitionElements();
     void showAllTransitionElements();
     void setExitTransitionStylesheetsEnabled(bool);
 
     unsigned countHitRegions(CanvasRenderingContext2D*);
 
     void forcePluginPlaceholder(HTMLElement* plugin, PassRefPtrWillBeRawPtr<DocumentFragment>, ExceptionState&);
     void forcePluginPlaceholder(HTMLElement* plugin, const PluginPlaceholderOptions&, ExceptionState&);
 
-    // Scheudle a forced Blink GC run (Oilpan) at the end of event loop.
+    void setScrollChain(ScrollState*, const WillBeHeapVector<RefPtrWillBeMember<Element>>& elements, ExceptionState&);
+
+    // Schedule a forced Blink GC run (Oilpan) at the end of event loop.
     // Note: This is designed to be only used from PerformanceTests/BlinkGC to explicitly measure only Blink GC time.
     //       Normal LayoutTests should use gc() instead as it would trigger both Blink GC and V8 GC.
     void forceBlinkGCWithoutV8GC();
 
     String selectedHTMLForClipboard();
     String selectedTextForClipboard();
 
 private:
     explicit Internals(Document*);
     Document* contextDocument() const;
     LocalFrame* frame() const;
     Vector<String> iconURLs(Document*, int iconTypesMask) const;
     PassRefPtrWillBeRawPtr<ClientRectList> annotatedRegions(Document*, bool draggable, ExceptionState&);
 
     DocumentMarker* markerAt(Node*, const String& markerType, unsigned index, ExceptionState&);
     Member<InternalRuntimeFlags> m_runtimeFlags;
 
     IterationSource* startIteration(ScriptState*, ExceptionState&) override;
 };
 
 } // namespace blink
 
 #endif // Internals_h