Reland of "Tracking reference filter mutation via SVGElementProxy"

third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.h

Index: third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.h
diff --git a/third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.h b/third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.h
index 6419c89be7e8687bdf727ac791e58f3d33b611d1..dc6926022eb7c78c7c2f04a3a615a37a273cd43c 100644
--- a/third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.h
+++ b/third_party/WebKit/Source/core/layout/svg/LayoutSVGResourceContainer.h
@@ -22,11 +22,11 @@
 
 #include "core/layout/svg/LayoutSVGHiddenContainer.h"
 #include "core/svg/SVGDocumentExtensions.h"
-#include "core/svg/SVGResourceClient.h"
-#include "platform/heap/Handle.h"
 
 namespace blink {
 
+class SVGElementProxySet;
+
 enum LayoutSVGResourceType {
   MaskerResourceType,
   MarkerResourceType,
@@ -63,8 +63,6 @@ class LayoutSVGResourceContainer : public LayoutSVGHiddenContainer {
   }
 
   void idChanged();
-  void addResourceClient(SVGResourceClient*);
-  void removeResourceClient(SVGResourceClient*);
 
   void invalidateCacheAndMarkForLayout(SubtreeLayoutScope* = nullptr);
 
@@ -86,9 +84,11 @@ class LayoutSVGResourceContainer : public LayoutSVGHiddenContainer {
   // Used from the invalidateClient/invalidateClients methods from classes,
   // inheriting from us.
   void markAllClientsForInvalidation(InvalidationMode);
-  void markAllResourceClientsForInvalidation();
   void markClientForInvalidation(LayoutObject*, InvalidationMode);
 
+  void notifyContentChanged();
+  virtual SVGElementProxySet* elementProxySet() { return nullptr; }
+
   void willBeDestroyed() override;
 
   bool m_isInLayout;
@@ -111,7 +111,6 @@ class LayoutSVGResourceContainer : public LayoutSVGHiddenContainer {
   // 22 padding bits available
 
   HashSet<LayoutObject*> m_clients;
-  PersistentHeapHashSet<WeakMember<SVGResourceClient>> m_resourceClients;
 };
 
 inline LayoutSVGResourceContainer* getLayoutSVGResourceContainerById(