Delay scrollContents until the next paint

Source/platform/scroll/ScrollView.h

Index: Source/platform/scroll/ScrollView.h
diff --git a/Source/platform/scroll/ScrollView.h b/Source/platform/scroll/ScrollView.h
index 753c618506af2d37d5fa755974bcac471651e567..3fed1f48602de964785781cef986c5a8392b32cc 100644
--- a/Source/platform/scroll/ScrollView.h
+++ b/Source/platform/scroll/ScrollView.h
@@ -144,6 +144,7 @@ public:
     // Functions for querying the current scrolled position (both as a point, a size, or as individual X and Y values).
     virtual IntPoint scrollPosition() const OVERRIDE { return visibleContentRect().location(); }
     IntSize scrollOffset() const { return toIntSize(visibleContentRect().location()); } // Gets the scrolled position as an IntSize. Convenient for adding to other sizes.
+    IntSize scrollDelta() const { return m_scrollDelta; }
     virtual IntPoint maximumScrollPosition() const OVERRIDE; // The maximum position we can be scrolled to.
     virtual IntPoint minimumScrollPosition() const OVERRIDE; // The minimum position we can be scrolled to.
     // Adjust the passed in scroll position to keep it between the minimum and maximum positions.
@@ -163,6 +164,7 @@ public:
     bool scroll(ScrollDirection, ScrollGranularity);
 
     // Scroll the actual contents of the view (either blitting or invalidating as needed).
+    void scrollContentsIfNeeded();
     void scrollContents(const IntSize& scrollDelta);
 
     // This gives us a means of blocking painting on our scrollbars until the first layout has occurred.
@@ -295,6 +297,7 @@ private:
 
     HashSet<RefPtr<Widget> > m_children;
 
+    IntSize m_scrollDelta;

[abarth-chromium, 2014/03/08 06:54:52]

m_pendingScrollDelta?

The word "pending" might hint that we're waiting to apply this scroll delta.

[ykyyip, 2014/03/11 01:59:39]

Done.

     IntSize m_scrollOffset; // FIXME: Would rather store this as a position, but we will wait to make this change until more code is shared.
     IntPoint m_cachedScrollPosition;
     IntSize m_contentsSize;
@@ -317,6 +320,7 @@ private:
     IntRect rectToCopyOnScroll() const;
 
     // Called when the scroll position within this view changes.  FrameView overrides this to generate repaint invalidations.
+    virtual void invalidateFixedElementsBeforeScrolling(const IntSize&, const IntRect&) { }
     virtual void repaintFixedElementsAfterScrolling() { }
     virtual void updateFixedElementsAfterScrolling() { }