Implement PaintLayer::scrollsWithViewport for SPv2.

third_party/WebKit/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 2856 matching lines @@
 
       scrollContentsIfNeededRecursive();
       DCHECK(RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled() ||
              lifecycle().state() >= DocumentLifecycle::CompositingClean);
 
       m_frame->host()->globalRootScrollerController().didUpdateCompositing();
 
       if (targetState >= DocumentLifecycle::PrePaintClean) {
         if (!RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled())
           invalidateTreeIfNeededRecursive();
-        if (view.compositor()->inCompositingMode())
-          scrollingCoordinator()->updateAfterCompositingChangeIfNeeded();
+
+        if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
+          if (view.compositor()->inCompositingMode())
+            scrollingCoordinator()->updateAfterCompositingChangeIfNeeded();
+        }
 
         updateCompositedSelectionIfNeeded();
       }
     }
 
     if (targetState >= DocumentLifecycle::PrePaintClean) {
       updatePaintProperties();
     }
 
     if (targetState == DocumentLifecycle::PaintClean) {
@@ skipping 1771 matching lines @@
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink