Changing animate to beginFrame and use struct rather than naked double to allow extension.

Source/core/page/AutoscrollController.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
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  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 #ifndef AutoscrollController_h
 #define AutoscrollController_h
 
 #include "platform/geometry/IntPoint.h"
+#include "public/platform/WebFrameTime.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace WebCore {
 
 class EventHandler;
 class LocalFrame;
 class FrameView;
 class Node;
 class Page;
 class PlatformMouseEvent;
 class RenderBox;
 class RenderObject;
 
 enum AutoscrollType {
     NoAutoscroll,
     AutoscrollForDragAndDrop,
     AutoscrollForSelection,
 #if OS(WIN)
     AutoscrollForPanCanStop,
     AutoscrollForPan,
 #endif
 };
 
 // AutscrollController handels autoscroll and pan scroll for EventHandler.
 class AutoscrollController {
 public:
     static PassOwnPtr<AutoscrollController> create(Page&);
 
-    void animate(double monotonicFrameBeginTime);
+    void animate(blink::WebFrameTime);
     bool autoscrollInProgress() const;
     bool autoscrollInProgress(const RenderBox*) const;
     bool panScrollInProgress() const;
     void startAutoscrollForSelection(RenderObject*);
     void stopAutoscroll();
     void stopAutoscrollIfNeeded(RenderObject*);
     void updateAutoscrollRenderer();
     void updateDragAndDrop(Node* targetNode, const IntPoint& eventPosition, double eventTime);
 #if OS(WIN)
     void handleMouseReleaseForPanScrolling(LocalFrame*, const PlatformMouseEvent&);
@@ skipping 15 matching lines @@
     IntPoint m_dragAndDropAutoscrollReferencePosition;
     double m_dragAndDropAutoscrollStartTime;
 #if OS(WIN)
     IntPoint m_panScrollStartPos;
 #endif
 };
 
 } // namespace WebCore
 
 #endif // AutoscrollController_h