Separate VisualViewport layer tree creation from attachment.

third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 444 matching lines @@
     rootFixedBackgroundsChanged();
     m_needsUpdateFixedBackground = false;
   }
 
   for (unsigned i = 0; i < layersNeedingPaintInvalidation.size(); i++) {
     forceRecomputeVisualRectsIncludingNonCompositingDescendants(
         layersNeedingPaintInvalidation[i]->layoutObject());
   }
 
   // Inform the inspector that the layer tree has changed.
-  if (m_layoutView.frame()->isMainFrame())
+  if (isMainFrame())
     probe::layerTreeDidChange(m_layoutView.frame());
 }
 
 void PaintLayerCompositor::updateClippingOnCompositorLayers() {
   bool shouldClip = !rootLayer()->hasRootScrollerAsDescendant();
   if (m_rootContentLayer) {
     // FIXME: with rootLayerScrolls, we probably don't even need
     // m_rootContentLayer?
     m_rootContentLayer->setMasksToBounds(
         !RuntimeEnabledFeatures::rootLayerScrollingEnabled() && shouldClip);
@@ skipping 240 matching lines @@
          m_layoutView.frameView()->shouldThrottleRendering());
 
   if (!m_rootContentLayer)
     return nullptr;
 
   // We skip dumping the scroll and clip layers to keep layerTreeAsText output
   // similar between platforms (unless we explicitly request dumping from the
   // root.
   GraphicsLayer* rootLayer = m_rootContentLayer.get();
   if (flags & LayerTreeIncludesRootLayer) {
-    if (m_layoutView.frame()->isMainFrame()) {
+    if (isMainFrame()) {
       while (rootLayer->parent())
         rootLayer = rootLayer->parent();
     } else {
       rootLayer = rootGraphicsLayer();
     }
   }
 
   return rootLayer->layerTreeAsJSON(flags);
 }
 
@@ skipping 302 matching lines @@
 
 bool PaintLayerCompositor::requiresScrollCornerLayer() const {
   return m_layoutView.frameView()->isScrollCornerVisible();
 }
 
 void PaintLayerCompositor::updateOverflowControlsLayers() {
   GraphicsLayer* controlsParent = m_overflowControlsHostLayer.get();
   // Main frame scrollbars should always be stuck to the sides of the screen (in
   // overscroll and in pinch-zoom), so make the parent for the scrollbars be the
   // viewport container layer.
-  if (m_layoutView.frame()->isMainFrame()) {
-    VisualViewport& visualViewport =
-        m_layoutView.frameView()->page()->frameHost().visualViewport();
-    controlsParent = visualViewport.containerLayer();
-  }
+  if (isMainFrame())
+    controlsParent = visualViewport().containerLayer();
 
   if (requiresHorizontalScrollbarLayer()) {
     if (!m_layerForHorizontalScrollbar) {
       m_layerForHorizontalScrollbar = GraphicsLayer::create(this);
     }
 
     if (m_layerForHorizontalScrollbar->parent() != controlsParent) {
       controlsParent->addChild(m_layerForHorizontalScrollbar.get());
 
       if (ScrollingCoordinator* scrollingCoordinator =
@@ skipping 48 matching lines @@
   m_layoutView.frameView()->positionScrollbarLayers();
 }
 
 void PaintLayerCompositor::ensureRootLayer() {
   RootLayerAttachment expectedAttachment =
       m_layoutView.frame()->isLocalRoot() ? RootLayerAttachedViaChromeClient
                                           : RootLayerAttachedViaEnclosingFrame;
   if (expectedAttachment == m_rootLayerAttachment)
     return;
 
+  if (isMainFrame())
+    visualViewport().createLayerTree();
+
   if (!m_rootContentLayer) {
     m_rootContentLayer = GraphicsLayer::create(this);
     IntRect overflowRect = m_layoutView.pixelSnappedLayoutOverflowRect();
     m_rootContentLayer->setSize(
         FloatSize(overflowRect.maxX(), overflowRect.maxY()));
     m_rootContentLayer->setPosition(FloatPoint());
     m_rootContentLayer->setOwnerNodeId(
         DOMNodeIds::idForNode(m_layoutView.node()));
   }
 
@@ skipping 191 matching lines @@
 }
 
 Page* PaintLayerCompositor::page() const {
   return m_layoutView.frameView()->frame().page();
 }
 
 DocumentLifecycle& PaintLayerCompositor::lifecycle() const {
   return m_layoutView.document().lifecycle();
 }
 
+bool PaintLayerCompositor::isMainFrame() const {
+  return m_layoutView.frame()->isMainFrame();
+}
+
+VisualViewport& PaintLayerCompositor::visualViewport() const {
+  return m_layoutView.frameView()->page()->frameHost().visualViewport();
+}
+
 String PaintLayerCompositor::debugName(
     const GraphicsLayer* graphicsLayer) const {
   String name;
   if (graphicsLayer == m_rootContentLayer.get()) {
     name = "Content Root Layer";
   } else if (graphicsLayer == m_overflowControlsHostLayer.get()) {
     name = "Frame Overflow Controls Host Layer";
   } else if (graphicsLayer == m_layerForHorizontalScrollbar.get()) {
     name = "Frame Horizontal Scrollbar Layer";
   } else if (graphicsLayer == m_layerForVerticalScrollbar.get()) {
     name = "Frame Vertical Scrollbar Layer";
   } else if (graphicsLayer == m_layerForScrollCorner.get()) {
     name = "Frame Scroll Corner Layer";
   } else if (graphicsLayer == m_containerLayer.get()) {
     name = "Frame Clipping Layer";
   } else if (graphicsLayer == m_scrollLayer.get()) {
     name = "Frame Scrolling Layer";
   } else {
     ASSERT_NOT_REACHED();
   }
 
   return name;
 }
 
 }  // namespace blink