Implement AudioTrack, AudioTrackList, VideoTrack, and VideoTrackList

Source/core/html/track/TrackBase.cpp

Index: Source/core/html/track/TrackBase.cpp
diff --git a/Source/core/html/track/TrackBase.cpp b/Source/core/html/track/TrackBase.cpp
index a11c065f41080f3d1d9d5b8d9e5b8b5c4a43105d..da2a33e31f3a210457d9a38910922878f72e005d 100644
--- a/Source/core/html/track/TrackBase.cpp
+++ b/Source/core/html/track/TrackBase.cpp
@@ -33,16 +33,25 @@
 
 namespace WebCore {
 
-TrackBase::TrackBase(Type type, const AtomicString& label, const AtomicString& language, const AtomicString& id)
-    : m_type(type)
+static blink::WebTrackId nextWebId()
+{
+    static blink::WebTrackId next = 0;
+    return ++next;
+}
+
+TrackBase::TrackBase(Type type, const AtomicString& label, const AtomicString& language, const String& id)
+    : m_webId(nextWebId())
+    , m_type(type)
     , m_label(label)
     , m_language(language)
     , m_id(id)
+    , m_mediaElement(0)
 {
 }
 
 TrackBase::~TrackBase()
 {
+    ASSERT(!m_mediaElement);
 }
 
 void TrackBase::setKind(const AtomicString& kind)
@@ -54,4 +63,3 @@ void TrackBase::setKind(const AtomicString& kind)
 }
 
 } // namespace WebCore
-