Mac: Update scrollbar size and input position during impl-overscroll

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 1544 matching lines @@
 {
     IntPoint newScrollPosition = adjustScrollPositionWithinRange(scrollPoint);
 
     if (newScrollPosition == scrollPosition())
         return;
 
     TemporaryChange<bool> changeInProgrammaticScroll(m_inProgrammaticScroll, false);
     notifyScrollPositionChanged(newScrollPosition);
 }
 
+void FrameView::setElasticOverscroll(const FloatSize& elasticOverscroll)
+{
+    m_elasticOverscroll = elasticOverscroll;
+    if (m_horizontalScrollbar && m_horizontalScrollbar->elasticOverscroll() != elasticOverscroll.width()) {
+        m_horizontalScrollbar->setElasticOverscroll(elasticOverscroll.width());
+        if (!m_scrollbarsSuppressed)
+            m_horizontalScrollbar->invalidate();
+    }
+    if (m_verticalScrollbar && m_verticalScrollbar->elasticOverscroll() != elasticOverscroll.width()) {
+        m_verticalScrollbar->setElasticOverscroll(elasticOverscroll.width());
+        if (!m_scrollbarsSuppressed)
+            m_verticalScrollbar->invalidate();
+    }
+}
+
 IntSize FrameView::layoutSize(IncludeScrollbarsInRect scrollbarInclusion) const
 {
     return scrollbarInclusion == ExcludeScrollbars ? excludeScrollbars(m_layoutSize) : m_layoutSize;
 }
 
 void FrameView::setLayoutSize(const IntSize& size)
 {
     ASSERT(!layoutSizeFixedToFrameSize());
 
     setLayoutSizeInternal(size);
@@ skipping 2406 matching lines @@
         return;
 
     ScrollableArea::setScrollOrigin(origin);
 
     // Update if the scroll origin changes, since our position will be different if the content size did not change.
     if (updatePositionAtAll && updatePositionSynchronously)
         updateScrollbars(scrollOffsetDouble());
 }
 
 } // namespace blink