Only scroll on main if the targeted frames need to scroll on main

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 807 matching lines @@
   if (layoutView.isNull())
     return false;
   if (m_frame->settings() &&
       m_frame->settings()->preferCompositingToLCDTextEnabled())
     return layoutView.compositor()->inCompositingMode();
   return false;
 }
 
 bool FrameView::shouldScrollOnMainThread() const {
   if (ScrollingCoordinator* sc = scrollingCoordinator()) {
-    if (sc->shouldUpdateScrollLayerPositionOnMainThread())
+    if (sc->shouldUpdateScrollLayerPositionOnMainThread(m_frame))
       return true;
   }
   return ScrollableArea::shouldScrollOnMainThread();
 }
 
 GraphicsLayer* FrameView::layerForScrolling() const {
   LayoutViewItem layoutView = this->layoutViewItem();
   if (layoutView.isNull())
     return nullptr;
   return layoutView.compositor()->frameScrollLayer();
@@ skipping 3820 matching lines @@
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.width();
 }
 
 int FrameView::initialViewportHeight() const {
   DCHECK(m_frame->isMainFrame());
   return m_initialViewportSize.height();
 }
 
 }  // namespace blink