Improve handling of duplicate id's for SVG resources

third_party/WebKit/Source/core/svg/SVGTreeScopeResources.h

 // Copyright 2017 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.
 
 #ifndef SVGTreeScopeResources_h
 #define SVGTreeScopeResources_h
 
 #include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 #include "wtf/HashMap.h"
@@ skipping 11 matching lines @@
 // element's id (which is used to identify a resource.)
 class SVGTreeScopeResources
     : public GarbageCollectedFinalized<SVGTreeScopeResources> {
   WTF_MAKE_NONCOPYABLE(SVGTreeScopeResources);
 
  public:
   explicit SVGTreeScopeResources(TreeScope*);
   ~SVGTreeScopeResources();
 
   void updateResource(const AtomicString& id, LayoutSVGResourceContainer*);
-  void removeResource(const AtomicString& id);
+  void updateResource(const AtomicString& oldId,
+                      const AtomicString& newId,
+                      LayoutSVGResourceContainer*);
+  void removeResource(const AtomicString& id, LayoutSVGResourceContainer*);
   LayoutSVGResourceContainer* resourceById(const AtomicString& id) const;
 
   // Pending resources are such which are referenced by any object in the SVG
   // document, but do NOT exist yet. For instance, dynamically built gradients
   // / patterns / clippers...
   void addPendingResource(const AtomicString& id, Element&);
   bool isElementPendingResource(Element&, const AtomicString& id) const;
   void notifyResourceAvailable(const AtomicString& id);
   void removeElementFromPendingResources(Element&);
 
   DECLARE_TRACE();
 
  private:
   void clearHasPendingResourcesIfPossible(Element&);
 
   using SVGPendingElements = HeapHashSet<Member<Element>>;
+  using ResourceMap = HashMap<AtomicString, LayoutSVGResourceContainer*>;
 
-  HashMap<AtomicString, LayoutSVGResourceContainer*> m_resources;
+  void registerResource(const AtomicString& id, LayoutSVGResourceContainer*);
+  void unregisterResource(ResourceMap::iterator);
+  void notifyPendingClients(const AtomicString& id);
+
+  ResourceMap m_resources;
   // Resources that are pending.
   HeapHashMap<AtomicString, Member<SVGPendingElements>> m_pendingResources;
+  Member<TreeScope> m_treeScope;
 };
 
 }  // namespace blink
 
 #endif  // SVGTreeScopeResources_h