Delay scrollContents until the next paint

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 07ccb28aa615c5404ea1573685f16da955149182..5442a45c4390e21028834177c659309d7ba90491 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -151,8 +151,6 @@ public:
     void setInputEventsTransformForEmulation(const IntSize&, float);
 
     virtual void setScrollPosition(const IntPoint&) OVERRIDE;
-    virtual void repaintFixedElementsAfterScrolling() OVERRIDE;
-    virtual void updateFixedElementsAfterScrolling() OVERRIDE;
     virtual bool shouldRubberBandInDirection(ScrollDirection) const OVERRIDE;
     virtual bool isRubberBandInProgress() const OVERRIDE;
     void setScrollPositionNonProgrammatically(const IntPoint&);
@@ -331,6 +329,7 @@ public:
     virtual GraphicsLayer* layerForScrollCorner() const OVERRIDE;
 
 protected:
+    virtual void scrollContentsIfNeeded();
     virtual bool scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect) OVERRIDE;
     virtual void scrollContentsSlowPath(const IntRect& updateRect) OVERRIDE;
 
@@ -394,6 +393,9 @@ private:
     void scrollPositionChanged();
     void didScrollTimerFired(Timer<FrameView>*);
 
+    void updateLayersAndCompositingAfterScrollIfNeeded();
+    void updateFixedElementRepaintRectsAfterScroll();
+
     bool hasCustomScrollbars() const;
     bool shouldUseCustomScrollbars(Element*& customScrollbarElement, LocalFrame*& customScrollbarFrame);