Reland of Fold compositing display items into contained drawings if the drawing is a singleton.

third_party/WebKit/Source/platform/graphics/paint/PaintController.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 "platform/graphics/paint/PaintController.h"
 
 #include "platform/TraceEvent.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
 #include "third_party/skia/include/core/SkPictureAnalyzer.h"
@@ skipping 137 matching lines @@
             --m_underInvalidationCheckingBegin;
         }
     }
 #endif
     m_newDisplayItemList.removeLast();
 
     if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
         m_newPaintChunks.decrementDisplayItemIndex();
 }
 
+const DisplayItem* PaintController::lastDisplayItem(unsigned offset)
+{
+    if (offset < m_newDisplayItemList.size())
+        return &m_newDisplayItemList[m_newDisplayItemList.size() - offset - 1];
+    return nullptr;
+}
+
 void PaintController::processNewItem(DisplayItem& displayItem)
 {
     DCHECK(!m_constructionDisabled);
 
 #if CHECK_DISPLAY_ITEM_CLIENT_ALIVENESS
     if (!isSkippingCache()) {
         if (displayItem.isCacheable()) {
             // Mark the client shouldKeepAlive under this PaintController.
             // The status will end after the new display items are committed.
             displayItem.client().beginShouldKeepAlive(this);
@@ skipping 367 matching lines @@
 {
     DCHECK(RuntimeEnabledFeatures::slimmingPaintUnderInvalidationCheckingEnabled());
 
     if (!isCheckingUnderInvalidation())
         return;
 
     const DisplayItem& newItem = m_newDisplayItemList.last();
     size_t oldItemIndex = m_underInvalidationCheckingBegin + m_skippedProbableUnderInvalidationCount;
     const DisplayItem* oldItem = oldItemIndex < m_currentPaintArtifact.getDisplayItemList().size() ? &m_currentPaintArtifact.getDisplayItemList()[oldItemIndex] : nullptr;
 
-    if (newItem.isCacheable() && !clientCacheIsValid(newItem.client())) {
-        showUnderInvalidationError("under-invalidation of PaintLayer: invalidated in cached subsequence", newItem, oldItem);
-        NOTREACHED();
-    }
-
     bool oldAndNewEqual = oldItem && newItem.equals(*oldItem);
     if (!oldAndNewEqual) {
         if (newItem.isBegin()) {
             // Temporarily skip mismatching begin display item which may be removed when we remove a no-op pair.
             ++m_skippedProbableUnderInvalidationCount;
             return;
         }
         if (newItem.isDrawing() && m_skippedProbableUnderInvalidationCount == 1) {
             DCHECK_GE(m_newDisplayItemList.size(), 2u);
             if (m_newDisplayItemList[m_newDisplayItemList.size() - 2].getType() == DisplayItem::BeginCompositing) {
@@ skipping 47 matching lines @@
 
 void PaintController::showDebugData() const
 {
     WTFLogAlways("current display item list: [%s]\n", displayItemListAsDebugString(m_currentPaintArtifact.getDisplayItemList()).utf8().data());
     WTFLogAlways("new display item list: [%s]\n", displayItemListAsDebugString(m_newDisplayItemList).utf8().data());
 }
 
 #endif // ifndef NDEBUG
 
 } // namespace blink