Separate VisualViewport layer tree creation from attachment.

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 3826 matching lines @@
 }
 
 void WebViewImpl::setRootGraphicsLayer(GraphicsLayer* graphicsLayer) {
   if (!m_layerTreeView)
     return;
 
   // In SPv2, setRootLayer is used instead.
   DCHECK(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
   VisualViewport& visualViewport = page()->frameHost().visualViewport();
-  visualViewport.attachToLayerTree(graphicsLayer);
+  visualViewport.attachLayerTree(graphicsLayer);
   if (graphicsLayer) {
     m_rootGraphicsLayer = visualViewport.rootGraphicsLayer();
     m_visualViewportContainerLayer = visualViewport.containerLayer();
     m_rootLayer = m_rootGraphicsLayer->platformLayer();
     updateDeviceEmulationTransform();
     m_layerTreeView->setRootLayer(*m_rootLayer);
     // We register viewport layers here since there may not be a layer
     // tree view prior to this point.
     registerViewportLayersWithCompositor();
 
@@ skipping 308 matching lines @@
   if (focusedFrame->localFrameRoot() != mainFrameImpl()->frame())
     return nullptr;
   return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const {
   return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink