Implement CSSOM Smooth Scroll API

Source/core/frame/FrameView.h

Index: Source/core/frame/FrameView.h
diff --git a/Source/core/frame/FrameView.h b/Source/core/frame/FrameView.h
index a2c9834394a8d6b7d09ca995497aaf57784cf5ce..f1363f01ee5ca9b2055ebd5ea6e764947c415c8c 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -71,7 +71,9 @@ public:
     virtual void invalidateRect(const IntRect&) OVERRIDE;
     virtual void setFrameRect(const IntRect&) OVERRIDE;
 
+    virtual bool registerForAnimation() OVERRIDE;
     virtual bool scheduleAnimation() OVERRIDE;
+    virtual void serviceScrollAnimations(double monotonicTime) OVERRIDE;
 
     Frame& frame() const { return *m_frame; }
 
@@ -157,7 +159,7 @@ public:
     virtual IntSize inputEventsOffsetForEmulation() const OVERRIDE;
     void setInputEventsTransformForEmulation(const IntSize&, float);
 
-    virtual void setScrollPosition(const IntPoint&) OVERRIDE;
+    virtual void setScrollPosition(const IntPoint&, ScrollBehavior = ScrollBehaviorInstant) OVERRIDE;
     virtual void repaintFixedElementsAfterScrolling() OVERRIDE;
     virtual void updateFixedElementsAfterScrolling() OVERRIDE;
     virtual bool shouldRubberBandInDirection(ScrollDirection) const OVERRIDE;
@@ -275,8 +277,10 @@ public:
     typedef HashSet<ScrollableArea*> ScrollableAreaSet;
     // Returns whether the scrollable area has just been newly added.
     bool addScrollableArea(ScrollableArea*);
+    bool addAnimatingScrollableArea(ScrollableArea*);
     // Returns whether the scrollable area has just been removed.
     bool removeScrollableArea(ScrollableArea*);
+    bool removeAnimatingScrollableArea(ScrollableArea*);
     bool containsScrollableArea(const ScrollableArea*) const;
     const ScrollableAreaSet* scrollableAreas() const { return m_scrollableAreas.get(); }
 
@@ -385,6 +389,7 @@ private:
     virtual GraphicsLayer* layerForHorizontalScrollbar() const OVERRIDE;
     virtual GraphicsLayer* layerForVerticalScrollbar() const OVERRIDE;
     virtual GraphicsLayer* layerForScrollCorner() const OVERRIDE;
+    virtual bool compositedScrollAnimationsEnabled() const OVERRIDE;
 
     void sendResizeEventIfNeeded();
 
@@ -508,6 +513,7 @@ private:
     IntSize m_maxAutoSize;
 
     OwnPtr<ScrollableAreaSet> m_scrollableAreas;
+    OwnPtr<ScrollableAreaSet> m_animatingScrollableAreas;
     OwnPtr<ResizerAreaSet> m_resizerAreas;
     OwnPtr<ViewportConstrainedObjectSet> m_viewportConstrainedObjects;