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

Source/core/html/track/VideoTrack.h

+// 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.
+
+#ifndef VideoTrack_h
+#define VideoTrack_h
+
+#include "bindings/v8/ScriptWrappable.h"
+#include "core/html/track/TrackBase.h"
+
+namespace WebCore {
+
+class HTMLMediaElement;
+
+class VideoTrack FINAL : public TrackBase, public ScriptWrappable {
+public:
+    static PassRefPtr<VideoTrack> create(HTMLMediaElement* mediaElement, const AtomicString& id, const AtomicString& kind, const AtomicString& label, const AtomicString& language)
+    {
+        return adoptRef(new VideoTrack(mediaElement, id, kind, label, language));
+    }
+    virtual ~VideoTrack();
+
+    bool selected() const { return m_selected; }
+    void setSelected(bool);
+
+    void clearSelected() { m_selected = false; }

[philipj_slow, 2014/03/13 10:00:04]

Ah, I guess this is to avoid multiple change events. Test please :) There are
tests in WebKit which we might steal, grep for "in-band" in LayoutTests/.

+
+    // Valid kind keywords.
+    static const AtomicString& alternativeKeyword();
+    static const AtomicString& captionsKeyword();
+    static const AtomicString& mainKeyword();
+    static const AtomicString& signKeyword();
+    static const AtomicString& subtitlesKeyword();
+    static const AtomicString& commentaryKeyword();
+
+private:
+    VideoTrack(HTMLMediaElement*, const AtomicString& id, const AtomicString& kind, const AtomicString& label, const AtomicString& language);
+
+    // TrackBase
+    virtual bool isValidKind(const AtomicString&) const OVERRIDE;
+    virtual AtomicString defaultKind() const OVERRIDE;
+
+    bool m_selected;
+};
+
+}
+
+#endif