[SPv2] Flatten property trees in PaintRecordBuilder into a single display list.

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

 // Copyright 2017 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/PaintChunksToCcLayer.h"
 
 #include "cc/paint/compositing_display_item.h"
 #include "cc/paint/display_item_list.h"
 #include "cc/paint/drawing_display_item.h"
 #include "cc/paint/filter_display_item.h"
@@ skipping 194 matching lines @@
     const gfx::Vector2dF& layerOffset,
     const DisplayItemList& displayItems,
     GeometryMapper& geometryMapper) {
   auto ccList = make_scoped_refptr(new cc::DisplayItemList);
 
   gfx::Transform counterOffset;
   counterOffset.Translate(-layerOffset.x(), -layerOffset.y());
   ccList->CreateAndAppendPairedBeginItem<cc::TransformDisplayItem>(
       counterOffset);
 
-  for (const auto& paintChunk : paintChunks) {
+  for (const auto* paintChunk : paintChunks) {
     const PropertyTreeState* state = &paintChunk->properties.propertyTreeState;
     PropertyTreeStateIterator iterator(*state);
     Vector<PropertyTreeState> pairedStates;
     for (; state && *state != layerState; state = iterator.next()) {
       if (state->innermostNode() != PropertyTreeState::None)
         pairedStates.push_back(*state);
     }
 
     // TODO(chrishtr): we can avoid some extra paired display items if
     // multiple PaintChunks share them. We can also collapse clips between
     // transforms into single clips in the same way that PaintLayerClipper does.
     Vector<EndDisplayItemType> endDisplayItems;
 
     recordPairedBeginDisplayItems(pairedStates, layerState, *ccList.get(),
                                   endDisplayItems, geometryMapper);
 
     for (const auto& displayItem : displayItems.itemsInPaintChunk(*paintChunk))
       appendDisplayItemToCcDisplayItemList(displayItem, ccList.get());
 
     recordPairedEndDisplayItems(endDisplayItems, ccList.get());
   }
 
   ccList->CreateAndAppendPairedEndItem<cc::EndTransformDisplayItem>();
 
   ccList->Finalize();
   return ccList;
 }
 
 }  // namespace blink