Slimming Paint phase 2 compositing algorithm plumbing

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 205 matching lines @@
 // Update the existing display items by removing invalidated entries, updating
 // repainted ones, and appending new items.
 // - For CachedDisplayItem, copy the corresponding cached DrawingDisplayItem;
 // - For SubtreeCachedDisplayItem, copy the cached display items between the
 //   corresponding BeginSubtreeDisplayItem and EndSubtreeDisplayItem (incl.);
 // - Otherwise, copy the new display item.
 //
 // The algorithm is O(|m_currentDisplayItems| + |m_newDisplayItems|).
 // Coefficients are related to the ratio of out-of-order [Subtree]CachedDisplayItems
 // and the average number of (Drawing|BeginSubtree)DisplayItems per client.
-void DisplayItemList::commitNewDisplayItems()
+//
+// TODO(pdr): Implement the DisplayListDiff algorithm for SlimmingPaintV2.
+void DisplayItemList::commitNewDisplayItems(DisplayListDiff*)
 {
     TRACE_EVENT2("blink,benchmark", "DisplayItemList::commitNewDisplayItems", "current_display_list_size", (int)m_currentDisplayItems.size(),
         "num_non_cached_new_items", (int)m_newDisplayItems.size() - m_numCachedItems);
 
     // These data structures are used during painting only.
     ASSERT(m_scopeStack.isEmpty());
     m_scopeStack.clear();
     m_nextScope = 1;
     ASSERT(!skippingCache());
 #if ENABLE(ASSERT)
@@ skipping 137 matching lines @@
     DisplayItemClient lastClient = nullptr;
     for (const DisplayItem& displayItem : m_currentDisplayItems) {
         if (displayItem.client() == lastClient)
             continue;
         lastClient = displayItem.client();
         if (!displayItem.skippedCache())
             m_validlyCachedClients.add(lastClient);
     }
 }
 
+void DisplayItemList::appendToWebDisplayItemList(WebDisplayItemList* list)
+{
+    for (const DisplayItem& item : m_currentDisplayItems)
+        item.appendToWebDisplayItemList(list);
+}
+
 void DisplayItemList::commitNewDisplayItemsAndAppendToWebDisplayItemList(WebDisplayItemList* list)
 {
     commitNewDisplayItems();
-    for (const DisplayItem& item : m_currentDisplayItems)
-        item.appendToWebDisplayItemList(list);
+    appendToWebDisplayItemList(list);
 }
 
 #if ENABLE(ASSERT)
 
 static void showUnderInvalidationError(const char* reason, const DisplayItem& displayItem)
 {
 #ifndef NDEBUG
     WTFLogAlways("%s: %s\nSee http://crbug.com/450725.", reason, displayItem.asDebugString().utf8().data());
 #else
     WTFLogAlways("%s. Run debug build to get more details\nSee http://crbug.com/450725.", reason);
@@ skipping 132 matching lines @@
 
 void DisplayItemList::replay(GraphicsContext& context)
 {
     TRACE_EVENT0("blink,benchmark", "DisplayItemList::replay");
     ASSERT(m_newDisplayItems.isEmpty());
     for (DisplayItem& displayItem : m_currentDisplayItems)
         displayItem.replay(context);
 }
 
 } // namespace blink