Implement AudioTrack, AudioTrackList, VideoTrack, and VideoTrackList

Source/core/html/track/AudioTrack.idl

Index: Source/core/html/track/AudioTrack.idl
diff --git a/Source/core/html/track/AudioTrack.idl b/Source/core/html/track/AudioTrack.idl
new file mode 100644
index 0000000000000000000000000000000000000000..1bf2f6e1979778402a15afda02b9e1b267e0cf93
--- /dev/null
+++ b/Source/core/html/track/AudioTrack.idl
@@ -0,0 +1,14 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+[
+    RuntimeEnabled=AudioVideoTracks,
+    WillBeGarbageCollected,
+] interface AudioTrack {
+  readonly attribute DOMString id;
+  readonly attribute DOMString kind;
+  readonly attribute DOMString label;
+  readonly attribute DOMString language;
+  attribute boolean enabled;
+};