Made root translation layer the root when using pinch virtual viewport.

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 3620 matching lines @@
 {
     if (m_pageOverlays && m_pageOverlays->remove(overlay) && m_pageOverlays->empty())
         m_pageOverlays = nullptr;
 }
 
 void WebViewImpl::setOverlayLayer(WebCore::GraphicsLayer* layer)
 {
     if (!m_rootGraphicsLayer)
         return;
 
+    if (pinchVirtualViewportEnabled()) {
+        m_page->mainFrame()->view()->renderView()->compositor()->setOverlayLayer(layer);
+        return;
+    }
+
+    // FIXME(bokan): This path goes away after virtual viewport pinch is enabled everywhere.
     if (!m_rootTransformLayer)
         m_rootTransformLayer = m_page->mainFrame()->view()->renderView()->compositor()->ensureRootTransformLayer();
 
     if (m_rootTransformLayer) {
         if (layer->parent() != m_rootTransformLayer)
             m_rootTransformLayer->addChild(layer);
     }
 }
 
 Element* WebViewImpl::focusedElement() const
@@ skipping 34 matching lines @@
 void WebViewImpl::setRootGraphicsLayer(GraphicsLayer* layer)
 {
     suppressInvalidations(true);
 
     if (pinchVirtualViewportEnabled()) {
         PinchViewport& pinchViewport = page()->frameHost().pinchViewport();
         pinchViewport.attachToLayerTree(layer, graphicsLayerFactory());
         if (layer) {
             m_rootGraphicsLayer = pinchViewport.rootGraphicsLayer();
             m_rootLayer = pinchViewport.rootGraphicsLayer()->platformLayer();
-            m_rootTransformLayer = 0;
+            m_rootTransformLayer = pinchViewport.rootTransformLayer();
         } else {
             m_rootGraphicsLayer = 0;
             m_rootLayer = 0;
             m_rootTransformLayer = 0;
         }
     } else {
         m_rootGraphicsLayer = layer;
         m_rootLayer = layer ? layer->platformLayer() : 0;
         m_rootTransformLayer = 0;
     }
@@ skipping 233 matching lines @@
     m_layerTreeView->setDeviceScaleFactor(deviceScaleFactor);
 }
 
 void WebViewImpl::updateRootLayerTransform()
 {
     // If we don't have a root graphics layer, we won't bother trying to find
     // or update the transform layer.
     if (!m_rootGraphicsLayer)
         return;
 
+    // FIXME(bokan): m_rootTransformLayer is always set here in pinch virtual viewport. This can go away once
+    // that's default everywhere.
     if (!m_rootTransformLayer)
         m_rootTransformLayer = m_page->mainFrame()->view()->renderView()->compositor()->ensureRootTransformLayer();
 
     if (m_rootTransformLayer) {
         WebCore::TransformationMatrix transform;
         transform.translate(m_rootLayerOffset.width, m_rootLayerOffset.height);
         transform = transform.scale(m_rootLayerScale);
         m_rootTransformLayer->setTransform(transform);
     }
 }
@@ skipping 92 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink