Update SelectorQuery constructor to adopt CSSSelectorList object

Update SelectorQuery constructor to adopt CSSSelectorList object instead of
copying it. This CL adds a adopt(CSSSelectorList&) factory function to
SelectorQuery class to make this behavior obvious.

Copying a CSSSelectorList is relatively expensive and it should therefore be
avoided when possible.

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/330713003

git-svn-id: svn://svn.chromium.org/blink/trunk@176116 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/dom/SelectorQuery.cpp

@@ -465,9 +465,14 @@ void SelectorDataList::execute(ContainerNode& rootNode, typename SelectorQueryTr
     findTraverseRootsAndExecute<SelectorQueryTrait>(rootNode, output);
 }
 
-SelectorQuery::SelectorQuery(const CSSSelectorList& selectorList)
-    : m_selectorList(selectorList)
+PassOwnPtr<SelectorQuery> SelectorQuery::adopt(CSSSelectorList& selectorList)
 {
+    return adoptPtr(new SelectorQuery(selectorList));
+}
+
+SelectorQuery::SelectorQuery(CSSSelectorList& selectorList)
+{
+    m_selectorList.adopt(selectorList);
     m_selectors.initialize(m_selectorList);
 }
 
@@ -511,10 +516,7 @@ SelectorQuery* SelectorQueryCache::add(const AtomicString& selectors, const Docu
     if (m_entries.size() == maximumSelectorQueryCacheSize)
         m_entries.remove(m_entries.begin());
 
-    OwnPtr<SelectorQuery> selectorQuery = adoptPtr(new SelectorQuery(selectorList));
-    SelectorQuery* rawSelectorQuery = selectorQuery.get();
-    m_entries.add(selectors, selectorQuery.release());
-    return rawSelectorQuery;
+    return m_entries.add(selectors, SelectorQuery::adopt(selectorList)).storedValue->value.get();
 }
 
 void SelectorQueryCache::invalidate()

third_party/WebKit/Source/core/dom/SelectorQuery.h

@@ -88,11 +88,14 @@ class SelectorQuery {
     WTF_MAKE_NONCOPYABLE(SelectorQuery);
     WTF_MAKE_FAST_ALLOCATED;
 public:
-    explicit SelectorQuery(const CSSSelectorList&);
+    static PassOwnPtr<SelectorQuery> adopt(CSSSelectorList&);
+
     bool matches(Element&) const;
     PassRefPtrWillBeRawPtr<NodeList> queryAll(ContainerNode& rootNode) const;
     PassRefPtrWillBeRawPtr<Element> queryFirst(ContainerNode& rootNode) const;
 private:
+    explicit SelectorQuery(CSSSelectorList&);
+
     SelectorDataList m_selectors;
     CSSSelectorList m_selectorList;
 };