A thread-safe Media Query Parser

Source/core/css/MediaQueryExp.h

Index: Source/core/css/MediaQueryExp.h
diff --git a/Source/core/css/MediaQueryExp.h b/Source/core/css/MediaQueryExp.h
index e21bbc9b9872e8725d91472d08a324a8f10ed925..cfb61b9a80431599cc718491b81fe6ab4cdbf0fd 100644
--- a/Source/core/css/MediaQueryExp.h
+++ b/Source/core/css/MediaQueryExp.h
@@ -29,11 +29,10 @@
 #ifndef MediaQueryExp_h
 #define MediaQueryExp_h
 
+#include "MediaFeatureNames.h"
 #include "core/css/CSSValue.h"
-#include "core/css/MediaFeatureNames.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
-#include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 class CSSParserValueList;
@@ -41,16 +40,16 @@ class CSSParserValueList;
 class MediaQueryExp {
     WTF_MAKE_FAST_ALLOCATED;
 public:
-    static PassOwnPtr<MediaQueryExp> create(const AtomicString& mediaFeature, CSSParserValueList*);
+    static PassOwnPtr<MediaQueryExp> create(const String& mediaFeature, CSSParserValueList*);
     ~MediaQueryExp();
 
-    AtomicString mediaFeature() const { return m_mediaFeature; }
+    String mediaFeature() const { return m_mediaFeature; }
 
     CSSValue* value() const { return m_value.get(); }
 
     bool operator==(const MediaQueryExp& other) const
     {
-        return (other.m_mediaFeature == m_mediaFeature)
+        return (other.m_mediaFeatureHash == m_mediaFeatureHash)
             && ((!other.m_value && !m_value)
                 || (other.m_value && m_value && other.m_value->equals(*m_value)));
     }
@@ -62,9 +61,10 @@ public:
     PassOwnPtr<MediaQueryExp> copy() const { return adoptPtr(new MediaQueryExp(*this)); }
 
 private:
-    MediaQueryExp(const AtomicString& mediaFeature, PassRefPtrWillBeRawPtr<CSSValue>);
+    MediaQueryExp(StringImpl*, PassRefPtrWillBeRawPtr<CSSValue>);
 
-    AtomicString m_mediaFeature;
+    String m_mediaFeature;
+    unsigned m_mediaFeatureHash;
     RefPtr<CSSValue> m_value;
 };