Revert of Client side display item cache flag

third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
index af1afd999974fb4c4a2a73a9c2141852d1bd0e0a..ea460b37c45f65eb686156fdf467fcde8a019ff4 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
@@ -138,8 +138,9 @@
 void PaintController::invalidateUntracked(const DisplayItemClient& client)
 {
     // This can be called during painting, but we can't invalidate already painted clients.
-    client.setDisplayItemsUncached();
     ASSERT(!m_newDisplayItemIndicesByClient.contains(&client));
+    updateValidlyCachedClientsIfNeeded();
+    m_validlyCachedClients.remove(&client);
 }
 
 void PaintController::invalidateAll()
@@ -147,7 +148,8 @@
     // Can only be called during layout/paintInvalidation, not during painting.
     ASSERT(m_newDisplayItemList.isEmpty());
     m_currentPaintArtifact.reset();
-    m_currentCacheGeneration.invalidate();
+    m_validlyCachedClients.clear();
+    m_validlyCachedClientsDirty = false;
 
     if (RuntimeEnabledFeatures::slimmingPaintV2Enabled() && m_trackedPaintInvalidationObjects)
         m_trackedPaintInvalidationObjects->append("##ALL##");
@@ -155,10 +157,10 @@
 
 bool PaintController::clientCacheIsValid(const DisplayItemClient& client) const
 {
-    ASSERT(DisplayItemClient::isAlive(client));
     if (skippingCache())
         return false;
-    return client.displayItemsAreCached(m_currentCacheGeneration);
+    updateValidlyCachedClientsIfNeeded();
+    return m_validlyCachedClients.contains(&client);
 }
 
 void PaintController::invalidatePaintOffset(const DisplayItemClient& client)
@@ -234,10 +236,12 @@
     for (; context.nextItemToIndex != currentEnd; ++context.nextItemToIndex) {
         const DisplayItem& item = *context.nextItemToIndex;
         ASSERT(item.hasValidClient());
-        if (id.matches(item))
-            return context.nextItemToIndex++;
-        if (item.isCacheable())
+        if (item.isCacheable() && clientCacheIsValid(item.client())) {
+            if (id.matches(item))
+                return context.nextItemToIndex++;
+
             addItemToIndexIfNeeded(item, context.nextItemToIndex - m_currentPaintArtifact.getDisplayItemList().begin(), context.displayItemIndicesByClient);
+        }
     }
     return currentEnd;
 }
@@ -292,6 +296,9 @@
         "num_non_cached_new_items", (int)m_newDisplayItemList.size() - m_numCachedNewItems);
     m_numCachedNewItems = 0;
 
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+        m_clientsCheckedPaintInvalidation.clear();
+
     // These data structures are used during painting only.
     ASSERT(m_scopeStack.isEmpty());
     m_scopeStack.clear();
@@ -313,9 +320,11 @@
 
         m_currentPaintArtifact = PaintArtifact(std::move(m_newDisplayItemList), m_newPaintChunks.releasePaintChunks());
         m_newDisplayItemList = DisplayItemList(kInitialDisplayItemListCapacityBytes);
-        updateCacheGeneration();
+        m_validlyCachedClientsDirty = true;
         return;
     }
+
+    updateValidlyCachedClientsIfNeeded();
 
     // Stores indices to valid DrawingDisplayItems in m_currentDisplayItems that have not been matched
     // by CachedDisplayItems during synchronized matching. The indexed items will be matched
@@ -394,7 +403,7 @@
     m_currentPaintArtifact = PaintArtifact(std::move(updatedList), m_newPaintChunks.releasePaintChunks());
 
     m_newDisplayItemList = DisplayItemList(kInitialDisplayItemListCapacityBytes);
-    updateCacheGeneration();
+    m_validlyCachedClientsDirty = true;
 }
 
 size_t PaintController::approximateUnsharedMemoryUsage() const
@@ -422,12 +431,22 @@
     return memoryUsage;
 }
 
-void PaintController::updateCacheGeneration()
-{
-    m_currentCacheGeneration = DisplayItemCacheGeneration::next();
+void PaintController::updateValidlyCachedClientsIfNeeded() const
+{
+    if (!m_validlyCachedClientsDirty)
+        return;
+
+    m_validlyCachedClients.clear();
+    m_validlyCachedClientsDirty = false;
+
+    const DisplayItemClient* lastAddedClient = nullptr;
     for (const DisplayItem& displayItem : m_currentPaintArtifact.getDisplayItemList()) {
-        if (displayItem.isCacheable())
-            displayItem.client().setDisplayItemsCached(m_currentCacheGeneration);
+        if (&displayItem.client() == lastAddedClient)
+            continue;
+        if (displayItem.isCacheable()) {
+            lastAddedClient = &displayItem.client();
+            m_validlyCachedClients.add(lastAddedClient);
+        }
     }
 }
 
@@ -494,7 +513,7 @@
         ASSERT_NOT_REACHED();
     }
 
-    if (newItem.isCacheable() && !clientCacheIsValid(newItem.client())) {
+    if (newItem.isCacheable() && !m_validlyCachedClients.contains(&newItem.client())) {
         showUnderInvalidationError(messagePrefix, "ERROR: under-invalidation: invalidated in cached subsequence", &newItem, &oldItem);
         ASSERT_NOT_REACHED();
     }