Use DOMSettableTokenList for {HTMLAnchorElement, HTMLAreaElement}.ping.

third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp b/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
index a5b29fa83b4746787b77ea9b5a6ab09ed6f15fe2..d75888ddd79f04c1de7c90c24f717c7eb8161c9c 100644
--- a/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLAnchorElement.cpp
@@ -50,9 +50,17 @@ HTMLAnchorElement::HTMLAnchorElement(const QualifiedName& tagName, Document& doc
     , m_linkRelations(0)
     , m_cachedVisitedLinkHash(0)
     , m_wasFocusedByMouse(false)
+    , m_ping(DOMSettableTokenList::create(this))

[philipj_slow, 2015/10/01 12:54:10]

This should mean a new heap-allocated object for every <a> in the world, and
there are a lot of those. I see that e.g. HTMLLinkElement does it like this, but
could this be lazily created in the ping() getter so that the price is only
payed for the few cases where the ping attribute is used?

 {
 }
 
+DEFINE_TRACE(HTMLAnchorElement)
+{
+    visitor->trace(m_ping);
+    HTMLElement::trace(visitor);
+    DOMSettableTokenListObserver::trace(visitor);
+}
+
 PassRefPtrWillBeRawPtr<HTMLAnchorElement> HTMLAnchorElement::create(Document& document)
 {
     return adoptRefWillBeNoop(new HTMLAnchorElement(aTag, document));
@@ -60,6 +68,9 @@ PassRefPtrWillBeRawPtr<HTMLAnchorElement> HTMLAnchorElement::create(Document& do
 
 HTMLAnchorElement::~HTMLAnchorElement()
 {
+#if !ENABLE(OILPAN)
+    m_ping->setObserver(nullptr);
+#endif
 }
 
 bool HTMLAnchorElement::supportsFocus() const
@@ -220,6 +231,8 @@ void HTMLAnchorElement::parseAttribute(const QualifiedName& name, const AtomicSt
         // Do nothing.
     } else if (name == relAttr) {
         setRel(value);
+    } else if (name == pingAttr) {
+        m_ping->setValue(value); 
     } else {
         HTMLElement::parseAttribute(name, value);
     }
@@ -320,17 +333,21 @@ bool HTMLAnchorElement::isLiveLink() const
 
 void HTMLAnchorElement::sendPings(const KURL& destinationURL) const
 {
-    const AtomicString& pingValue = getAttribute(pingAttr);
-    if (pingValue.isNull() || !document().settings() || !document().settings()->hyperlinkAuditingEnabled())
+    if (m_ping->value().isNull() || !document().settings() || !document().settings()->hyperlinkAuditingEnabled())
         return;
 
     UseCounter::count(document(), UseCounter::HTMLAnchorElementPingAttribute);
 
-    SpaceSplitString pingURLs(pingValue, SpaceSplitString::ShouldNotFoldCase);
+    const SpaceSplitString& pingURLs = m_ping->tokens();
     for (unsigned i = 0; i < pingURLs.size(); i++)
         PingLoader::sendLinkAuditPing(document().frame(), document().completeURL(pingURLs[i]), destinationURL);
 }
 
+DOMSettableTokenList* HTMLAnchorElement::ping() const
+{
+    return m_ping.get();
+}
+
 void HTMLAnchorElement::handleClick(Event* event)
 {
     event->setDefaultHandled();
@@ -373,6 +390,11 @@ void HTMLAnchorElement::handleClick(Event* event)
     }
 }
 
+void HTMLAnchorElement::valueChanged()
+{
+    setSynchronizedLazyAttribute(pingAttr, m_ping->value());
+}
+
 bool isEnterKeyKeydownEvent(Event* event)
 {
     return event->type() == EventTypeNames::keydown && event->isKeyboardEvent() && toKeyboardEvent(event)->keyIdentifier() == "Enter";