Initial implementation of AudioTrack, AudioTrackList, VideoTrack, and VideoTrackList.

Source/core/html/track/TrackBase.h

Index: Source/core/html/track/TrackBase.h
diff --git a/Source/core/html/track/TrackBase.h b/Source/core/html/track/TrackBase.h
index b291c68db363fd0a7b2e59c5c97e2c86a39aa651..df5d41e286fc423097d8482781d08a8e1734fad2 100644
--- a/Source/core/html/track/TrackBase.h
+++ b/Source/core/html/track/TrackBase.h
@@ -31,6 +31,8 @@
 
 namespace WebCore {
 
+class HTMLMediaElement;
+
 class TrackBase : public RefCounted<TrackBase> {
 public:
     virtual ~TrackBase();
@@ -47,11 +49,14 @@ public:
     AtomicString language() const { return m_language; }
     void setLanguage(const AtomicString& language) { m_language = language; }
 
-    AtomicString id() const { return m_id; }
-    void setId(const AtomicString& id) { m_id = id; }
+    String id() const { return m_id; }
+    void setId(const String& id) { m_id = id; }
+
+    void setMediaElement(HTMLMediaElement* mediaElement) { m_mediaElement = mediaElement; }
+    HTMLMediaElement* mediaElement() const { return m_mediaElement; }
 
 protected:
-    TrackBase(Type, const AtomicString& label, const AtomicString& language, const AtomicString& id);
+    TrackBase(Type, const AtomicString& label, const AtomicString& language, const String& id);
 
     virtual bool isValidKind(const AtomicString&) const = 0;
     virtual AtomicString defaultKind() const = 0;
@@ -61,7 +66,8 @@ private:
     AtomicString m_kind;
     AtomicString m_label;
     AtomicString m_language;
-    AtomicString m_id;
+    String m_id;
+    HTMLMediaElement* m_mediaElement;
 };
 
 } // namespace WebCore