Move scroll paint property nodes to be owned by the transform tree

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/compositing/PaintArtifactCompositor.h"
 
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/picture_layer.h"
 #include "cc/playback/compositing_display_item.h"
@@ skipping 579 matching lines @@
     if (currentState->hasDirectCompositingReasons())
       return false;
   }
   return false;
 }
 
 bool PaintArtifactCompositor::mightOverlap(
     const PaintChunk& paintChunk,
     const PendingLayer& candidatePendingLayer,
     GeometryMapper& geometryMapper) {
-  PropertyTreeState rootPropertyTreeState(
-      TransformPaintPropertyNode::root(), ClipPaintPropertyNode::root(),
-      EffectPaintPropertyNode::root(), ScrollPaintPropertyNode::root());
+  PropertyTreeState rootPropertyTreeState(TransformPaintPropertyNode::root(),
+                                          ClipPaintPropertyNode::root(),
+                                          EffectPaintPropertyNode::root());
 
   FloatRect paintChunkScreenVisualRect =
       geometryMapper.localToAncestorVisualRect(
           paintChunk.bounds, paintChunk.properties.propertyTreeState,
           rootPropertyTreeState);
 
   FloatRect pendingLayerScreenVisualRect =
       geometryMapper.localToAncestorVisualRect(
           candidatePendingLayer.bounds, candidatePendingLayer.propertyTreeState,
           rootPropertyTreeState);
@@ skipping 88 matching lines @@
   collectPendingLayers(paintArtifact, pendingLayers, geometryMapper);
 
   Vector<std::unique_ptr<ContentLayerClientImpl>> newContentLayerClients;
   newContentLayerClients.reserveCapacity(paintArtifact.paintChunks().size());
   for (const PendingLayer& pendingLayer : pendingLayers) {
     gfx::Vector2dF layerOffset;
     scoped_refptr<cc::Layer> layer = compositedLayerForPendingLayer(
         paintArtifact, pendingLayer, layerOffset, newContentLayerClients,
         rasterChunkInvalidations, storeDebugInfo, geometryMapper);
 
-    int transformId = propertyTreeManager.ensureCompositorTransformNode(
-        pendingLayer.propertyTreeState.transform());
-    int scrollId = propertyTreeManager.ensureCompositorScrollNode(
-        pendingLayer.propertyTreeState.scroll());
+    const auto* transform = pendingLayer.propertyTreeState.transform();
+    int transformId =
+        propertyTreeManager.ensureCompositorTransformNode(transform);
     int clipId = propertyTreeManager.ensureCompositorClipNode(
         pendingLayer.propertyTreeState.clip());
     int effectId = propertyTreeManager.switchToEffectNode(
         *pendingLayer.propertyTreeState.effect());
 
     layer->set_offset_to_transform_parent(layerOffset);
     layer->SetElementId(pendingLayer.propertyTreeState.compositorElementId());
 
     m_rootLayer->AddChild(layer);
     layer->set_property_tree_sequence_number(
         PropertyTreeManager::kPropertyTreeSequenceNumber);
     layer->SetTransformTreeIndex(transformId);
     layer->SetClipTreeIndex(clipId);
     layer->SetEffectTreeIndex(effectId);
-    layer->SetScrollTreeIndex(scrollId);
+    if (const auto* scrollNode = transform->scrollNode()) {
+      layer->SetScrollTreeIndex(
+          propertyTreeManager.ensureCompositorScrollNode(scrollNode));
+    }
 
     layer->SetShouldCheckBackfaceVisibility(pendingLayer.backfaceHidden);
 
     if (m_extraDataForTestingEnabled)
       m_extraDataForTesting->contentLayers.push_back(layer);
   }
   m_contentLayerClients.clear();
   m_contentLayerClients.swap(newContentLayerClients);
 
   // Mark the property trees as having been rebuilt.
   layerTree->property_trees()->sequence_number =
       PropertyTreeManager::kPropertyTreeSequenceNumber;
   layerTree->property_trees()->needs_rebuild = false;
   layerTree->property_trees()->ResetCachedData();
 }
 
 #ifndef NDEBUG
 void PaintArtifactCompositor::showDebugData() {
   LOG(ERROR) << layersAsJSON(LayerTreeIncludesDebugInfo)
                     ->toPrettyJSONString()
                     .utf8()
                     .data();
 }
 #endif
 
 }  // namespace blink