Reland of place pinch scrollbars with regular scrollbars.

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 658 matching lines @@
 bool FrameView::usesCompositedScrolling() const
 {
     LayoutView* layoutView = this->layoutView();
     if (!layoutView)
         return false;
     if (m_frame->settings() && m_frame->settings()->preferCompositingToLCDTextEnabled())
         return layoutView->compositor()->inCompositingMode();
     return false;
 }
 
+GraphicsLayer* FrameView::layerForScrollbarContainer() const
+{
+    if (m_frame->isMainFrame())
+        return page()->frameHost().visualViewport().layerForScrollbarContainer();
+    return layerForContainer();
+}
+
 GraphicsLayer* FrameView::layerForScrolling() const
 {
     LayoutView* layoutView = this->layoutView();
     if (!layoutView)
         return nullptr;
     return layoutView->compositor()->frameScrollLayer();
 }
 
 GraphicsLayer* FrameView::layerForHorizontalScrollbar() const
 {
@@ skipping 3269 matching lines @@
 
     if (!graphicsLayer)
         return;
 
     DeprecatedPaintLayer::mapRectToPaintInvalidationBacking(localFrame->contentLayoutObject(), paintInvalidationContainer, viewRect);
 
     graphicsLayerTimingRequests.add(graphicsLayer, Vector<std::pair<int64_t, WebRect>>()).storedValue->value.append(std::make_pair(m_frame->frameID(), enclosingIntRect(viewRect)));
 }
 
 } // namespace blink