Revert of Tracking filter mutation via SVGElementProxy

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

Index: third_party/WebKit/Source/core/svg/SVGElementProxy.h
diff --git a/third_party/WebKit/Source/core/svg/SVGElementProxy.h b/third_party/WebKit/Source/core/svg/SVGElementProxy.h
deleted file mode 100644
index 7fcea97a416013ca77bfd5eda97730e27dba84d9..0000000000000000000000000000000000000000
--- a/third_party/WebKit/Source/core/svg/SVGElementProxy.h
+++ /dev/null
@@ -1,138 +0,0 @@
-// Copyright 2016 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 SVGElementProxy_h
-#define SVGElementProxy_h
-
-#include "core/fetch/DocumentResource.h"
-#include "platform/heap/Handle.h"
-#include "wtf/text/AtomicString.h"
-#include "wtf/text/WTFString.h"
-
-namespace blink {
-
-class Document;
-class SVGElement;
-class SVGResourceClient;
-class TreeScope;
-
-// A proxy to an SVGElement. Allows access to an element with a certain 'id',
-// and provides its clients with notifications when the proxied element
-// changes.
-//
-// SVGElements can be referenced using CSS, for example like:
-//
-//   filter: url(#baz);
-//
-//    or
-//
-//   filter: url(foo.com/bar.svg#baz);
-//
-// SVGElementProxy provide a mechanism to persistently reference an SVGElement
-// in such cases - regardless of if the proxied element reside in the same
-// document (read: tree scope) or in an external (resource) document. Loading
-// events related to external documents case needs be handled by the clients
-// (SVGResourceClient's default implementation does this.)
-//
-// The proxy uses an 'id' (c.f getElementById) to determine which element to
-// proxy. The id is looked up in the TreeScope provided by the client for a
-// same-document reference and in the TreeScope of the Document for a external
-// document reference.
-//
-// For same document references, the proxy will track changes that could affect
-// the 'id' lookup, to handle elements being added, removed or having their
-// 'id' mutated. (This does not apply for the external document case because
-// it's assumed they will not mutate after load, due to scripts not being run
-// etc.)
-//
-// SVGElementProxys are created by CSSURIValue, and have SVGResourceClients as
-// a means to deliver change notifications. Clients that are interested in
-// change notifications hence need to register a SVGResourceClient with the
-// proxy. Most commonly this registration would take place when the
-// ComputedStyle changes.
-//
-// Registration of a client does not establish a link to the proxied element
-// right away. That is instead deferred until findElement(...) is called on the
-// SVGElementProxy. At this point, the proxy will be registered with the
-// element if the lookup is successful. (For external references lookups will
-// not be registered, per the same assumption as mentioned above.)
-//
-// As content is mutated, clients will get notified via the proxied element
-// which in turn will notify all registered proxies, which will notify all
-// registered clients.
-//
-// <event> -> SVG...Element -> SVGElementProxy(0..N) -> SVGResourceClient(0..N)
-//
-class SVGElementProxy : public GarbageCollectedFinalized<SVGElementProxy> {
- public:
-  // Create a proxy to an element in the same document. (See also
-  // SVGURLReferenceResolver and the definition of 'local url'.)
-  static SVGElementProxy* create(const AtomicString& id) {
-    return new SVGElementProxy(id);
-  }
-
-  // Create a proxy to an element in a different document (indicated by |url|.)
-  static SVGElementProxy* create(const String& url, const AtomicString& id) {
-    return new SVGElementProxy(url, id);
-  }
-  virtual ~SVGElementProxy();
-
-  void addClient(SVGResourceClient*);
-  void removeClient(SVGResourceClient*);
-
-  // Resolve a potentially external document reference.
-  void resolve(Document&);
-
-  // Returns the proxied element, or null if the proxy is invalid.
-  SVGElement* findElement(TreeScope&);
-
-  // Notify the proxy that the structure of the subtree rooted at the proxied
-  // element has mutated. This should generally only be called via a proxy set.
-  void contentChanged(TreeScope&);
-
-  const AtomicString& id() const { return m_id; }
-
-  DECLARE_VIRTUAL_TRACE();
-
- private:
-  explicit SVGElementProxy(const AtomicString&);
-  SVGElementProxy(const String&, const AtomicString&);
-
-  TreeScope* treeScopeForLookup(TreeScope&) const;
-
-  class IdObserver;
-
-  HeapHashMap<Member<SVGResourceClient>, Member<IdObserver>> m_clients;
-  HeapHashMap<Member<TreeScope>, Member<IdObserver>> m_observers;
-  Member<DocumentResource> m_document;
-  AtomicString m_id;
-  // URL for resolving references to external resource documents. Contains an
-  // absolute URL to the resource to load. Cleared when a load has been
-  // initiated. Ignored if m_isLocal is true.
-  String m_url;
-  bool m_isLocal;
-};
-
-// Collection of SVGElementProxys. This is hosted by elements that can be
-// subject to proxies (currently only SVGFilterElement), and is mainly a helper
-// for dealing with the many-to-one structure of SVGElementProxy.
-class SVGElementProxySet : public GarbageCollected<SVGElementProxySet> {
- public:
-  void add(SVGElementProxy&);
-  bool isEmpty() const;
-
-  // Notify proxy clients that the (content of the) proxied element has
-  // changed.
-  void notifyContentChanged(TreeScope&);
-
-  DECLARE_TRACE();
-
- private:
-  using ProxySet = HeapHashSet<WeakMember<SVGElementProxy>>;
-  ProxySet m_elementProxies;
-};
-
-}  // namespace blink
-
-#endif  // SVGElementProxy_h