Add a new mechanism for watching SVGElement 'href' targets

third_party/WebKit/Source/core/svg/SVGMPathElement.cpp

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "core/svg/SVGMPathElement.h"
 
+#include "core/SVGNames.h"
 #include "core/dom/Document.h"
+#include "core/dom/IdTargetObserver.h"
 #include "core/svg/SVGAnimateMotionElement.h"
 #include "core/svg/SVGPathElement.h"
-#include "core/svg/SVGTreeScopeResources.h"
 
 namespace blink {
 
 inline SVGMPathElement::SVGMPathElement(Document& document)
     : SVGElement(SVGNames::mpathTag, document), SVGURIReference(this) {
   ASSERT(RuntimeEnabledFeatures::smilEnabled());
 }
 
 DEFINE_TRACE(SVGMPathElement) {
+  visitor->trace(m_targetIdObserver);
   SVGElement::trace(visitor);
   SVGURIReference::trace(visitor);
 }
 
 DEFINE_NODE_FACTORY(SVGMPathElement)
 
 SVGMPathElement::~SVGMPathElement() {}
 
 void SVGMPathElement::buildPendingResource() {
   clearResourceReferences();
   if (!isConnected())
     return;
-
-  AtomicString id;
-  Element* target = SVGURIReference::targetElementFromIRIString(
-      hrefString(), treeScope(), &id);
-  if (!target) {
-    // Do not register as pending if we are already pending this resource.
-    if (treeScope().ensureSVGTreeScopedResources().isElementPendingResource(
-            *this, id))
-      return;
-    if (!id.isEmpty()) {
-      treeScope().ensureSVGTreeScopedResources().addPendingResource(id, *this);
-      DCHECK(hasPendingResources());
-    }
-  } else if (isSVGPathElement(target)) {
+  Element* target = observeTarget(m_targetIdObserver, *this);
+  if (isSVGPathElement(target)) {
     // Register us with the target in the dependencies map. Any change of
     // hrefElement that leads to relayout/repainting now informs us, so we can
     // react to it.
     addReferenceTo(toSVGElement(target));
   }
-
   targetPathChanged();
 }
 
 void SVGMPathElement::clearResourceReferences() {
+  unobserveTarget(m_targetIdObserver);
   removeAllOutgoingReferences();
 }
 
 Node::InsertionNotificationRequest SVGMPathElement::insertedInto(
     ContainerNode* rootParent) {
   SVGElement::insertedInto(rootParent);
   if (rootParent->isConnected())
     buildPendingResource();
   return InsertionDone;
 }
@@ skipping 23 matching lines @@
 void SVGMPathElement::targetPathChanged() {
   notifyParentOfPathChange(parentNode());
 }
 
 void SVGMPathElement::notifyParentOfPathChange(ContainerNode* parent) {
   if (isSVGAnimateMotionElement(parent))
     toSVGAnimateMotionElement(parent)->updateAnimationPath();
 }
 
 }  // namespace blink