Separate VisualViewport layer tree creation from attachment.

This paves the way for deferring attachment.  With root layer scrolling the
layer passed to WebViewImpl::setRootGraphicsLayer will be the LayoutView's main
GraphicsLayer, which does not exist until after the compositing update.

BUG=698464
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2735543002
Cr-Commit-Position: refs/heads/master@{#454934}

third_party/WebKit/LayoutTests/FlagExpectations/enable-slimming-paint-v2

@@ -449,7 +449,7 @@ Bug(none) compositing/video/video-poster.html [ Crash Failure ]
 Bug(none) compositing/video/video-reflection.html [ Crash Failure  ]
 Bug(none) compositing/visibility/layer-visible-content.html [ Failure ]
 Bug(none) compositing/visibility/overlays-persist-on-navigation.html [ Crash ]
-Bug(none) compositing/visibility/overlays.html [ Crash ]
+Bug(none) compositing/visibility/overlays.html [ Failure Crash ]
 Bug(none) compositing/visibility/visibility-image-layers-dynamic.html [ Crash Failure ]
 Bug(none) compositing/visibility/visibility-image-layers.html [ Failure ]
 Bug(none) compositing/visibility/visibility-simple-video-layer.html [ Failure ]
@@ -595,7 +595,7 @@ Bug(none) fast/events/scale-and-scroll-window.html [ Crash Timeout ]
 Bug(none) fast/events/scroll-after-click-on-tab-index.html [ Failure ]
 Bug(none) fast/events/space-scroll-textinput-canceled.html [ Failure ]
 Bug(none) fast/events/touch/compositor-touch-hit-rects-animation.html [ Failure ]
-Bug(none) fast/events/touch/compositor-touch-hit-rects-global.html [ Crash ]
+Bug(none) fast/events/touch/compositor-touch-hit-rects-global.html [ Failure Crash ]
 Bug(none) fast/events/touch/compositor-touch-hit-rects-many.html [ Failure ]
 Bug(none) fast/events/touch/compositor-touch-hit-rects-non-composited-scroll.html [ Failure ]
 Bug(none) fast/events/touch/compositor-touch-hit-rects-scroll.html [ Failure ]
@@ -1588,7 +1588,7 @@ crbug.com/675805 fast/text/complex-text-opacity.html [ Failure ]
 
 # Failures due to frame scrollbars not painted
 crbug.com/589279 css3/blending/background-blend-mode-data-uri-svg-image.html [ Failure ]
- 
+
 # Need to write SPv2 version of this code.
 crbug.com/157218 compositing/overflow/border-radius-styles-with-composited-child.html [ Failure ]
 crbug.com/157218 compositing/overflow/siblings-with-border-radius-ancestor.html [ Failure ]
@@ -1645,7 +1645,7 @@ Bug(none) virtual/threaded/inspector/ [ Skip ]
 Bug(none) virtual/threaded/fast/scroll-behavior/ [ Skip ]
 Bug(none) virtual/threaded/compositing/visibility/layer-visible-content.html [ Failure ]
 Bug(none) virtual/threaded/compositing/visibility/overlays-persist-on-navigation.html [ Crash ]
-Bug(none) virtual/threaded/compositing/visibility/overlays.html [ Crash ]
+Bug(none) virtual/threaded/compositing/visibility/overlays.html [ Failure Crash ]
 Bug(none) virtual/threaded/compositing/visibility/visibility-image-layers-dynamic.html [ Crash Failure ]
 Bug(none) virtual/threaded/compositing/visibility/visibility-image-layers.html [ Failure ]
 Bug(none) virtual/threaded/compositing/visibility/visibility-simple-video-layer.html [ Failure ]

third_party/WebKit/Source/core/frame/VisualViewport.cpp

@@ -319,30 +319,57 @@ bool VisualViewport::magnifyScaleAroundAnchor(float magnifyDelta,
   return true;
 }
 
-// Modifies the top of the graphics layer tree to add layers needed to support
-// the inner/outer viewport fixed-position model for pinch zoom. When finished,
-// the tree will look like this (with * denoting added layers):
-//
-// *rootTransformLayer
-//  +- *innerViewportContainerLayer (fixed pos container)
-//     +- *overscrollElasticityLayer
-//     |   +- *pageScaleLayer
-//     |       +- *innerViewportScrollLayer
-//     |           +-- overflowControlsHostLayer (root layer)
-//     |               | [ owned by PaintLayerCompositor ]
-//     |               +-- outerViewportContainerLayer (fixed pos container)
-//     |               |     [frame container layer in PaintLayerCompositor]
-//     |               |   +-- outerViewportScrollLayer
-//     |               |       | [frame scroll layer in PaintLayerCompositor]
-//     |               |       +-- content layers ...
-//     +- *PageOverlay for InspectorOverlay
-//     +- *PageOverlay for ColorOverlay
-//     +- horizontalScrollbarLayer [ owned by PaintLayerCompositor ]
-//     +- verticalScrollbarLayer [ owned by PaintLayerCompositor ]
-//     +- scroll corner (non-overlay only) [ owned by PaintLayerCompositor ]
-//
-void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot) {
-  TRACE_EVENT1("blink", "VisualViewport::attachToLayerTree",
+void VisualViewport::createLayerTree() {
+  if (m_innerViewportScrollLayer)
+    return;
+
+  DCHECK(!m_overlayScrollbarHorizontal && !m_overlayScrollbarVertical &&
+         !m_overscrollElasticityLayer && !m_pageScaleLayer &&
+         !m_innerViewportContainerLayer);
+
+  // FIXME: The root transform layer should only be created on demand.
+  m_rootTransformLayer = GraphicsLayer::create(this);
+  m_innerViewportContainerLayer = GraphicsLayer::create(this);
+  m_overscrollElasticityLayer = GraphicsLayer::create(this);
+  m_pageScaleLayer = GraphicsLayer::create(this);
+  m_innerViewportScrollLayer = GraphicsLayer::create(this);
+  m_overlayScrollbarHorizontal = GraphicsLayer::create(this);
+  m_overlayScrollbarVertical = GraphicsLayer::create(this);
+
+  ScrollingCoordinator* coordinator = frameHost().page().scrollingCoordinator();
+  DCHECK(coordinator);
+  coordinator->setLayerIsContainerForFixedPositionLayers(
+      m_innerViewportScrollLayer.get(), true);
+
+  // Set masks to bounds so the compositor doesn't clobber a manually
+  // set inner viewport container layer size.
+  m_innerViewportContainerLayer->setMasksToBounds(
+      frameHost().page().settings().getMainFrameClipsContent());
+  m_innerViewportContainerLayer->setSize(FloatSize(m_size));
+
+  m_innerViewportScrollLayer->platformLayer()->setScrollClipLayer(
+      m_innerViewportContainerLayer->platformLayer());
+  m_innerViewportScrollLayer->platformLayer()->setUserScrollable(true, true);
+  if (mainFrame()) {
+    if (Document* document = mainFrame()->document()) {
+      m_innerViewportScrollLayer->setElementId(createCompositorElementId(
+          DOMNodeIds::idForNode(document), CompositorSubElementId::Viewport));
+    }
+  }
+
+  m_rootTransformLayer->addChild(m_innerViewportContainerLayer.get());
+  m_innerViewportContainerLayer->addChild(m_overscrollElasticityLayer.get());
+  m_overscrollElasticityLayer->addChild(m_pageScaleLayer.get());
+  m_pageScaleLayer->addChild(m_innerViewportScrollLayer.get());
+
+  // Ensure this class is set as the scroll layer's ScrollableArea.
+  coordinator->scrollableAreaScrollLayerDidChange(this);
+
+  initializeScrollbars();
+}
+
+void VisualViewport::attachLayerTree(GraphicsLayer* currentLayerTreeRoot) {
+  TRACE_EVENT1("blink", "VisualViewport::attachLayerTree",
                "currentLayerTreeRoot", (bool)currentLayerTreeRoot);
   if (!currentLayerTreeRoot) {
     if (m_innerViewportScrollLayer)
@@ -354,53 +381,7 @@ void VisualViewport::attachToLayerTree(GraphicsLayer* currentLayerTreeRoot) {
       currentLayerTreeRoot->parent() == m_innerViewportScrollLayer.get())
     return;
 
-  if (!m_innerViewportScrollLayer) {
-    ASSERT(!m_overlayScrollbarHorizontal && !m_overlayScrollbarVertical &&
-           !m_overscrollElasticityLayer && !m_pageScaleLayer &&
-           !m_innerViewportContainerLayer);
-
-    // FIXME: The root transform layer should only be created on demand.
-    m_rootTransformLayer = GraphicsLayer::create(this);
-    m_innerViewportContainerLayer = GraphicsLayer::create(this);
-    m_overscrollElasticityLayer = GraphicsLayer::create(this);
-    m_pageScaleLayer = GraphicsLayer::create(this);
-    m_innerViewportScrollLayer = GraphicsLayer::create(this);
-    m_overlayScrollbarHorizontal = GraphicsLayer::create(this);
-    m_overlayScrollbarVertical = GraphicsLayer::create(this);
-
-    ScrollingCoordinator* coordinator =
-        frameHost().page().scrollingCoordinator();
-    ASSERT(coordinator);
-    coordinator->setLayerIsContainerForFixedPositionLayers(
-        m_innerViewportScrollLayer.get(), true);
-
-    // Set masks to bounds so the compositor doesn't clobber a manually
-    // set inner viewport container layer size.
-    m_innerViewportContainerLayer->setMasksToBounds(
-        frameHost().page().settings().getMainFrameClipsContent());
-    m_innerViewportContainerLayer->setSize(FloatSize(m_size));
-
-    m_innerViewportScrollLayer->platformLayer()->setScrollClipLayer(
-        m_innerViewportContainerLayer->platformLayer());
-    m_innerViewportScrollLayer->platformLayer()->setUserScrollable(true, true);
-    if (mainFrame()) {
-      if (Document* document = mainFrame()->document()) {
-        m_innerViewportScrollLayer->setElementId(createCompositorElementId(
-            DOMNodeIds::idForNode(document), CompositorSubElementId::Viewport));
-      }
-    }
-
-    m_rootTransformLayer->addChild(m_innerViewportContainerLayer.get());
-    m_innerViewportContainerLayer->addChild(m_overscrollElasticityLayer.get());
-    m_overscrollElasticityLayer->addChild(m_pageScaleLayer.get());
-    m_pageScaleLayer->addChild(m_innerViewportScrollLayer.get());
-
-    // Ensure this class is set as the scroll layer's ScrollableArea.
-    coordinator->scrollableAreaScrollLayerDidChange(this);
-
-    initializeScrollbars();
-  }
-
+  DCHECK(m_innerViewportScrollLayer);
   m_innerViewportScrollLayer->removeAllChildren();
   m_innerViewportScrollLayer->addChild(currentLayerTreeRoot);
 }

third_party/WebKit/Source/core/frame/VisualViewport.h

@@ -62,6 +62,25 @@ class LocalFrame;
 // mechanisms. Its contents is the page's main FrameView, which corresponds to
 // the outer viewport. The inner viewport is always contained in the outer
 // viewport and can pan within it.
+//
+// When attached, the tree will look like this:
+//
+// VV::m_rootTransformLayer
+//  +- VV::m_innerViewportContainerLayer
+//     +- VV::m_overscrollElasticityLayer
+//     |   +- VV::m_pageScaleLayer
+//     |       +- VV::m_innerViewportScrollLayer
+//     |           +-- PLC::m_overflowControlsHostLayer
+//     |               +-- PLC::m_containerLayer (fixed pos container)
+//     |                   +-- PLC::m_scrollLayer
+//     |                       +-- PLC::m_rootContentLayer
+//     |                           +-- LayoutView CompositedLayerMapping layers
+//     +- PageOverlay for InspectorOverlay
+//     +- PageOverlay for ColorOverlay
+//     +- PLC::m_layerForHorizontalScrollbar
+//     +- PLC::m_layerForVerticalScrollbar
+//     +- PLC::m_layerForScrollCorner (non-overlay only)
+//
 class CORE_EXPORT VisualViewport final
     : public GarbageCollectedFinalized<VisualViewport>,
       public GraphicsLayerClient,
@@ -76,7 +95,8 @@ class CORE_EXPORT VisualViewport final
 
   DECLARE_VIRTUAL_TRACE();
 
-  void attachToLayerTree(GraphicsLayer*);
+  void createLayerTree();
+  void attachLayerTree(GraphicsLayer*);
 
   GraphicsLayer* rootGraphicsLayer() { return m_rootTransformLayer.get(); }
   GraphicsLayer* containerLayer() {

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

@@ -462,7 +462,7 @@ void PaintLayerCompositor::updateIfNeeded() {
   }
 
   // Inform the inspector that the layer tree has changed.
-  if (m_layoutView.frame()->isMainFrame())
+  if (isMainFrame())
     probe::layerTreeDidChange(m_layoutView.frame());
 }
 
@@ -723,7 +723,7 @@ std::unique_ptr<JSONObject> PaintLayerCompositor::layerTreeAsJSON(
   // root.
   GraphicsLayer* rootLayer = m_rootContentLayer.get();
   if (flags & LayerTreeIncludesRootLayer) {
-    if (m_layoutView.frame()->isMainFrame()) {
+    if (isMainFrame()) {
       while (rootLayer->parent())
         rootLayer = rootLayer->parent();
     } else {
@@ -1046,11 +1046,8 @@ void PaintLayerCompositor::updateOverflowControlsLayers() {
   // 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) {
@@ -1119,6 +1116,9 @@ void PaintLayerCompositor::ensureRootLayer() {
   if (expectedAttachment == m_rootLayerAttachment)
     return;
 
+  if (isMainFrame())
+    visualViewport().createLayerTree();
+
   if (!m_rootContentLayer) {
     m_rootContentLayer = GraphicsLayer::create(this);
     IntRect overflowRect = m_layoutView.pixelSnappedLayoutOverflowRect();
@@ -1330,6 +1330,14 @@ 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;

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

@@ -43,6 +43,7 @@ class Page;
 class LayoutPart;
 class Scrollbar;
 class ScrollingCoordinator;
+class VisualViewport;
 
 enum CompositingUpdateType {
   CompositingUpdateNone,
@@ -244,6 +245,9 @@ class CORE_EXPORT PaintLayerCompositor final : public GraphicsLayerClient {
   // instance if any, else nullptr.
   Scrollbar* graphicsLayerToScrollbar(const GraphicsLayer*) const;
 
+  bool isMainFrame() const;
+  VisualViewport& visualViewport() const;
+
   LayoutView& m_layoutView;
   std::unique_ptr<GraphicsLayer> m_rootContentLayer;
 

third_party/WebKit/Source/core/loader/EmptyClients.cpp

@@ -115,7 +115,7 @@ void EmptyChromeClient::attachRootGraphicsLayer(GraphicsLayer* layer,
   Page* page = localRoot ? localRoot->page() : nullptr;
   if (!page)
     return;
-  page->frameHost().visualViewport().attachToLayerTree(layer);
+  page->frameHost().visualViewport().attachLayerTree(layer);
 }
 
 String EmptyChromeClient::acceptLanguages() {

third_party/WebKit/Source/web/WebViewImpl.cpp

@@ -3844,7 +3844,7 @@ void WebViewImpl::setRootGraphicsLayer(GraphicsLayer* graphicsLayer) {
   DCHECK(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
   VisualViewport& visualViewport = page()->frameHost().visualViewport();
-  visualViewport.attachToLayerTree(graphicsLayer);
+  visualViewport.attachLayerTree(graphicsLayer);
   if (graphicsLayer) {
     m_rootGraphicsLayer = visualViewport.rootGraphicsLayer();
     m_visualViewportContainerLayer = visualViewport.containerLayer();