Support slotchange event

third_party/WebKit/Source/core/html/HTMLSlotElement.h

 /*
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 
 namespace blink {
 
 class AssignedNodesOptions;
 
 class CORE_EXPORT HTMLSlotElement final : public HTMLElement {
     DEFINE_WRAPPERTYPEINFO();
 public:
     DECLARE_NODE_FACTORY(HTMLSlotElement);
 
-    const HeapVector<Member<Node>>& assignedNodes() const { ASSERT(!needsDistributionRecalc()); return m_assignedNodes; }
+    const HeapVector<Member<Node>>& assignedNodes() const { return m_assignedNodes; }
     const HeapVector<Member<Node>>& getDistributedNodes();
     const HeapVector<Member<Node>> assignedNodesForBinding(const AssignedNodesOptions&);
 
     Node* firstDistributedNode() const { return m_distributedNodes.isEmpty() ? nullptr : m_distributedNodes.first().get(); }
     Node* lastDistributedNode() const { return m_distributedNodes.isEmpty() ? nullptr : m_distributedNodes.last().get(); }
 
     Node* distributedNodeNextTo(const Node&) const;
     Node* distributedNodePreviousTo(const Node&) const;
 
     void appendAssignedNode(Node&);
+    void willUpdateAssignment();
     void appendDistributedNode(Node&);
     void appendDistributedNodesFrom(const HTMLSlotElement& other);
     void willUpdateDistribution();
+    void appendFallbackNode(Node&);
+    void willUpdateFallback();
 
-    bool hasSlotChangeEventListener();
-
+    void didUpdateAssignment();
+    void updateFallbackNodes();
     void updateDistributedNodesWithFallback();
     void didUpdateDistribution();
 
+    void fireSlotChangeEvent();
+
     void attach(const AttachContext& = AttachContext()) final;
     void detach(const AttachContext& = AttachContext()) final;
 
     void attributeChanged(const QualifiedName&, const AtomicString& oldValue, const AtomicString& newValue, AttributeModificationReason = ModifiedDirectly) final;
 
     short tabIndex() const override;
     AtomicString name() const;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     HTMLSlotElement(Document&);
 
+    enum AssignmentState {
+        AssignmentOnGoing,
+        AssignmentDone,
+        AssignmentChanged,
+        AssignmentUnchanged
+    };
+
     enum DistributionState {
         DistributionOnGoing,
         DistributionDone,
         DistributionChanged,
         DistributionUnchanged
     };
 
     void clearDistribution();
     void childrenChanged(const ChildrenChange&) final;
     InsertionNotificationRequest insertedInto(ContainerNode*) final;
     void removedFrom(ContainerNode*) final;
     void willRecalcStyle(StyleRecalcChange) final;
 
     void dispatchSlotChangeEvent();
+    bool assignmentChanged();
     bool distributionChanged();
+    bool fallbackChanged();
 
     HeapVector<Member<Node>> m_assignedNodes;
     HeapVector<Member<Node>> m_distributedNodes;
+    HeapVector<Member<Node>> m_fallbackNodes;
     HeapHashMap<Member<const Node>, size_t> m_distributedIndices;
+    HeapVector<Member<Node>> m_oldAssignedNodes;
     // TODO(hayato): Remove m_oldDistibutedNodes and make SlotAssignment check the diffirence between old and new distributed nodes for each slot to save the memories.
     HeapVector<Member<Node>> m_oldDistributedNodes;
+    HeapVector<Member<Node>> m_oldFallbackNodes;
     DistributionState m_distributionState;
+    AssignmentState m_assignmentState;
+    bool m_slotchangeEventAdded;
 };
 
 } // namespace blink
 
 #endif // HTMLSlotElement_h