Reduce a shadow root object's size by not inheriting DoublyLinkedList

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.h

 /*
  * Copyright (C) 2011 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.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 15 matching lines @@
 
 #ifndef ShadowRoot_h
 #define ShadowRoot_h
 
 #include "core/CoreExport.h"
 #include "core/dom/ContainerNode.h"
 #include "core/dom/DocumentFragment.h"
 #include "core/dom/Element.h"
 #include "core/dom/TreeScope.h"
 #include "core/dom/shadow/SlotAssignment.h"
-#include "wtf/DoublyLinkedList.h"
-#include <iosfwd>
 
 namespace blink {
 
 class Document;
 class ElementShadow;
 class ExceptionState;
 class HTMLShadowElement;
 class InsertionPoint;
 class ShadowRootRareData;
 class ShadowRootRareDataV0;
 class StyleSheetList;
 
 enum class ShadowRootType {
     UserAgent,
     V0,
     Open,
     Closed
 };
 
-class CORE_EXPORT ShadowRoot final : public DocumentFragment, public TreeScope, public DoublyLinkedListNode<ShadowRoot> {
+class CORE_EXPORT ShadowRoot final : public DocumentFragment, public TreeScope {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(ShadowRoot);
-    friend class WTF::DoublyLinkedListNode<ShadowRoot>;
 public:
     // FIXME: Current implementation does not work well if a shadow root is dynamically created.
     // So multiple shadow subtrees in several elements are prohibited.
     // See https://github.com/w3c/webcomponents/issues/102 and http://crbug.com/234020
     static ShadowRoot* create(Document& document, ShadowRootType type)
     {
         return new ShadowRoot(document, type);
     }
 
     void recalcStyle(StyleRecalcChange);
 
     // Disambiguate between Node and TreeScope hierarchies; TreeScope's implementation is simpler.
     using TreeScope::document;
     using TreeScope::getElementById;
 
     // TODO(kochi): crbug.com/507413 In non-Oilpan, host() may return null during queued
     // event handling (e.g. during execCommand()).
     Element* host() const { return toElement(parentOrShadowHostNode()); }
     ElementShadow* owner() const { return host() ? host()->shadow() : 0; }
 
-    ShadowRoot* youngerShadowRoot() const { return prev(); }
+    ShadowRoot* youngerShadowRoot() const;
+    ShadowRoot* olderShadowRoot() const;
+    ShadowRoot* olderShadowRootForBindings() const;
 
-    ShadowRoot* olderShadowRootForBindings() const;
+    void setYoungerShadowRoot(ShadowRoot&);
+    void setOlderShadowRoot(ShadowRoot&);
 
     String mode() const { return (type() == ShadowRootType::V0 || type() == ShadowRootType::Open) ? "open" : "closed"; };
 
     bool isOpenOrV0() const { return type() == ShadowRootType::V0 || type() == ShadowRootType::Open; }
 
     bool isV1() const { return type() == ShadowRootType::Open || type() == ShadowRootType::Closed; }
 
     bool isYoungest() const { return !youngerShadowRoot(); }
     bool isOldest() const { return !olderShadowRoot(); }
 
@@ skipping 34 matching lines @@
     HTMLSlotElement* assignedSlotFor(const Node& node) const
     {
         DCHECK(m_slotAssignment);
         return m_slotAssignment->assignedSlotFor(node);
     }
 
     // Make protected methods from base class public here.
     using TreeScope::setDocument;
     using TreeScope::setParentTreeScope;
 
-public:
     Element* activeElement() const;
 
-    ShadowRoot* olderShadowRoot() const { return next(); }
-
     String innerHTML() const;
     void setInnerHTML(const String&, ExceptionState&);
 
     Node* cloneNode(bool, ExceptionState&);
 
     StyleSheetList* styleSheets();
 
     void setDelegatesFocus(bool flag) { m_delegatesFocus = flag; }
     bool delegatesFocus() const { return m_delegatesFocus; }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     ShadowRoot(Document&, ShadowRootType);
     ~ShadowRoot() override;
 
     void childrenChanged(const ChildrenChange&) override;
 
-    ShadowRootRareData* ensureShadowRootRareData();
-    ShadowRootRareDataV0* ensureShadowRootRareDataV0();
+    ShadowRootRareData& ensureShadowRootRareData();
+    ShadowRootRareDataV0& ensureShadowRootRareDataV0();
 
     void addChildShadowRoot();
     void removeChildShadowRoot();
     void invalidateDescendantInsertionPoints();
 
     // ShadowRoots should never be cloned.
     Node* cloneNode(bool) override { return nullptr; }
 
     // FIXME: This shouldn't happen. https://bugs.webkit.org/show_bug.cgi?id=88834
     bool isOrphan() const { return !host(); }
 
     void invalidateDescendantSlots();
     unsigned descendantSlotCount() const;
 
-    Member<ShadowRoot> m_prev;
-    Member<ShadowRoot> m_next;
     Member<ShadowRootRareData> m_shadowRootRareData;
     Member<ShadowRootRareDataV0> m_shadowRootRareDataV0;
-
     Member<SlotAssignment> m_slotAssignment;
     unsigned m_numberOfStyles : 26;
     unsigned m_type : 2;
     unsigned m_registeredWithParentShadowRoot : 1;
     unsigned m_descendantInsertionPointsIsValid : 1;
     unsigned m_delegatesFocus : 1;
     unsigned m_descendantSlotsIsValid : 1;
 };
 
 inline Element* ShadowRoot::activeElement() const
@@ skipping 11 matching lines @@
 
 DEFINE_NODE_TYPE_CASTS(ShadowRoot, isShadowRoot());
 DEFINE_TYPE_CASTS(ShadowRoot, TreeScope, treeScope, treeScope->rootNode().isShadowRoot(), treeScope.rootNode().isShadowRoot());
 DEFINE_TYPE_CASTS(TreeScope, ShadowRoot, shadowRoot, true, true);
 
 CORE_EXPORT std::ostream& operator<<(std::ostream&, const ShadowRootType&);
 
 } // namespace blink
 
 #endif // ShadowRoot_h