Implement AudioTrack, AudioTrackList, VideoTrack, and VideoTrackList

Source/core/html/track/VideoTrackList.idl

Index: Source/core/html/track/VideoTrackList.idl
diff --git a/Source/core/html/track/VideoTrackList.idl b/Source/core/html/track/VideoTrackList.idl
new file mode 100644
index 0000000000000000000000000000000000000000..aaa2f5c3367b24bb26d715bb1256829b4f6d8e70
--- /dev/null
+++ b/Source/core/html/track/VideoTrackList.idl
@@ -0,0 +1,16 @@
+// 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,

[haraken, 2014/06/03 05:48:29]

I guess you need [WillBeGarbageCollected]

[haraken, 2014/06/03 05:50:13]

sorry, ignore my comment. As sof@ mentioned, we currently need
[WillBeGarbageCollected], but it's going to be removed shortly.

+] interface VideoTrackList : EventTarget {
+  readonly attribute unsigned long length;
+  getter VideoTrack (unsigned long index);
+  VideoTrack? getTrackById(DOMString id);
+  readonly attribute long selectedIndex;
+
+  attribute EventHandler onchange;
+  attribute EventHandler onaddtrack;
+  attribute EventHandler onremovetrack;
+};