WIP for display item list backed by ListContainer

Source/platform/graphics/paint/DisplayItemList.cpp

 // Copyright 2014 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 "config.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 
 #include "platform/NotImplemented.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/TraceEvent.h"
@@ skipping 42 matching lines @@
     DisplayItemIndicesByClientMap::iterator it = m_newDisplayItemIndicesByClient.find(m_newDisplayItems.last().client());
     if (it != m_newDisplayItemIndicesByClient.end()) {
         Vector<size_t>& indices = it->value;
         if (!indices.isEmpty() && indices.last() == (m_newDisplayItems.size() - 1))
             indices.removeLast();
     }
 #endif
     m_newDisplayItems.removeLast();
 }
 
-void DisplayItemList::add(WTF::PassOwnPtr<DisplayItem> displayItem)
+void DisplayItemList::processNewItem(DisplayItem* displayItem)
 {
     ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
     ASSERT(!m_constructionDisabled);
     ASSERT(!skippingCache() || !displayItem->isCached());
 
     if (DisplayItem::isCachedType(displayItem->type()))
         ++m_numCachedItems;
 
 #if ENABLE(ASSERT)
-    // Verify noop begin/end pairs have been removed.
-    if (!m_newDisplayItems.isEmpty() && m_newDisplayItems.last().isBegin() && !m_newDisplayItems.last().drawsContent())
-        ASSERT(!displayItem->isEndAndPairedWith(m_newDisplayItems.last().type()));
+// TODO(pdr): Reenable this assert. Note that the item has already been appended.
+//    // Verify noop begin/end pairs have been removed.
+//    if (!m_newDisplayItems.isEmpty() && m_newDisplayItems.last().isBegin() && !m_newDisplayItems.last().drawsContent())
+//        ASSERT(!displayItem->isEndAndPairedWith(m_newDisplayItems.last().type()));
 #endif
 
     if (!m_scopeStack.isEmpty())
         displayItem->setScope(m_scopeStack.last().id, m_scopeStack.last().client);
 
 #if ENABLE(ASSERT)
     size_t index = findMatchingItemFromIndex(displayItem->id(), displayItem->type(), m_newDisplayItemIndicesByClient, m_newDisplayItems);
     if (index != kNotFound) {
 #ifndef NDEBUG
         showDebugData();
         WTFLogAlways("DisplayItem %s has duplicated id with previous %s (index=%d)\n",
             displayItem->asDebugString().utf8().data(), m_newDisplayItems[index].asDebugString().utf8().data(), static_cast<int>(index));
 #endif
         ASSERT_NOT_REACHED();
     }
-    addItemToIndex(displayItem->client(), displayItem->type(), m_newDisplayItems.size(), m_newDisplayItemIndicesByClient);
+    addItemToIndex(displayItem->client(), displayItem->type(), m_newDisplayItems.size() - 1, m_newDisplayItemIndicesByClient);
 #endif // ENABLE(ASSERT)
 
     ASSERT(!displayItem->skippedCache()); // Only DisplayItemList can set the flag.
     if (skippingCache())
         displayItem->setSkippedCache();
-
-    m_newDisplayItems.append(displayItem);
 }
 
 void DisplayItemList::beginScope(DisplayItemClient client)
 {
     ClientScopeIdMap::iterator it = m_clientScopeIdMap.find(client);
     int scopeId;
     if (it == m_clientScopeIdMap.end()) {
         m_clientScopeIdMap.add(client, 0);
         scopeId = 0;
     } else {
@@ skipping 147 matching lines @@
     if (RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled()) {
         // Under-invalidation checking requires a full index of m_currentDisplayItems.
         size_t i = 0;
         for (const auto& item : m_currentDisplayItems) {
             addItemToIndex(item.client(), item.type(), i, displayItemIndicesByClient);
             ++i;
         }
     }
 #endif // ENABLE(ASSERT)
 
-    DisplayItems updatedList;
+    // TODO(pdr): Use some smarts to set this initial capacity.
+    DisplayItems updatedList(kInitialDisplayItemsCapacity);
     DisplayItems::Iterator currentIt = m_currentDisplayItems.begin();
     DisplayItems::Iterator currentEnd = m_currentDisplayItems.end();
     for (DisplayItems::Iterator newIt = m_newDisplayItems.begin(); newIt != m_newDisplayItems.end(); ++newIt) {
         DisplayItems::ItemHandle newDisplayItem = *newIt;
         DisplayItem::Type matchingType = newDisplayItem.type();
         if (DisplayItem::isCachedType(newDisplayItem.type()))
             matchingType = DisplayItem::cachedTypeToDrawingType(matchingType);
         bool isSynchronized = currentIt != currentEnd
             && !currentIt->isGone()
             && currentIt->id().equalToExceptForType(newDisplayItem.id(), matchingType);
@@ skipping 219 matching lines @@
 
 void DisplayItemList::replay(GraphicsContext& context) const
 {
     TRACE_EVENT0("blink,benchmark", "DisplayItemList::replay");
     ASSERT(m_newDisplayItems.isEmpty());
     for (auto& displayItem : m_currentDisplayItems)
         displayItem.replay(context);
 }
 
 } // namespace blink