Reland of "Tracking reference filter mutation via SVGElementProxy"

third_party/WebKit/Source/core/css/CSSURIValue.cpp

 // Copyright 2015 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.
 
 #include "core/css/CSSURIValue.h"
 
 #include "core/css/CSSMarkup.h"
 #include "core/dom/Document.h"
-#include "core/fetch/FetchInitiatorTypeNames.h"
-#include "core/fetch/FetchRequest.h"
-#include "core/fetch/ResourceFetcher.h"
-#include "wtf/text/WTFString.h"
+#include "core/svg/SVGElementProxy.h"
+#include "core/svg/SVGURIReference.h"
 
 namespace blink {
 
 CSSURIValue::CSSURIValue(const String& urlString)
-    : CSSValue(URIClass), m_url(urlString), m_loadRequested(false) {}
+    : CSSValue(URIClass), m_url(urlString) {}
 
 CSSURIValue::~CSSURIValue() {}
 
-DocumentResource* CSSURIValue::load(Document& document) const {
-  if (!m_loadRequested) {
-    m_loadRequested = true;
-
-    FetchRequest request(ResourceRequest(document.completeURL(m_url)),
-                         FetchInitiatorTypeNames::css);
-    m_document =
-        DocumentResource::fetchSVGDocument(request, document.fetcher());
+SVGElementProxy& CSSURIValue::ensureElementProxy(Document& document) const {
+  if (m_proxy)
+    return *m_proxy;
+  SVGURLReferenceResolver resolver(m_url, document);
+  AtomicString fragmentId = resolver.fragmentIdentifier();
+  if (resolver.isLocal()) {
+    m_proxy = SVGElementProxy::create(fragmentId);
+  } else {
+    m_proxy =
+        SVGElementProxy::create(resolver.absoluteUrl().getString(), fragmentId);
   }
-  return m_document;
+  return *m_proxy;
 }
 
 String CSSURIValue::customCSSText() const {
   return serializeURI(m_url);
 }
 
 bool CSSURIValue::equals(const CSSURIValue& other) const {
   return m_url == other.m_url;
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(CSSURIValue) {
-  visitor->trace(m_document);
+  visitor->trace(m_proxy);
   CSSValue::traceAfterDispatch(visitor);
 }
 
 }  // namespace blink