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

Source/core/html/track/TrackListBase.h

Index: Source/core/html/track/TrackListBase.h
diff --git a/Source/core/html/track/TrackListBase.h b/Source/core/html/track/TrackListBase.h
new file mode 100644
index 0000000000000000000000000000000000000000..124ab6f5f2afe1048124e6af97d4f15c793fa789
--- /dev/null
+++ b/Source/core/html/track/TrackListBase.h
@@ -0,0 +1,124 @@
+// 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 TrackListBase_h
+#define TrackListBase_h
+
+#include "core/events/EventTarget.h"
+
+#include "core/html/HTMLMediaElement.h"
+#include "core/html/track/TrackEvent.h"
+
+namespace WebCore {
+
+template<class T>
+class TrackListBase : public RefCounted<TrackListBase<T> >, public EventTargetWithInlineData {
+    REFCOUNTED_EVENT_TARGET(TrackListBase<T>);
+
+public:
+    explicit TrackListBase(HTMLMediaElement* mediaElement)
+        : m_mediaElement(mediaElement)
+    {
+    }
+
+    virtual ~TrackListBase()
+    {
+        ASSERT(m_tracks.isEmpty());
+        ASSERT(!m_mediaElement);
+    }
+
+    unsigned length() const { return m_tracks.size(); }
+    PassRefPtr<T> anonymousIndexedGetter(unsigned index) const
+    {
+        if (index >= m_tracks.size())
+            return nullptr;
+        return m_tracks[index];
+    }
+
+    PassRefPtr<T> getTrackById(const String& id) const
+    {
+        for (unsigned i = 0; i < m_tracks.size(); ++i) {
+            if (m_tracks[i]->id() == id)
+                return m_tracks[i];
+        }
+
+        return nullptr;
+    }
+
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(change);
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(addtrack);
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(removetrack);
+
+    // EventTarget interface
+    virtual ExecutionContext* executionContext() const OVERRIDE
+    {
+        if (m_mediaElement)
+            return m_mediaElement->executionContext();
+        return 0;
+    }
+
+    void shutdown()
+    {
+        removeAll();
+        m_mediaElement = 0;
+    }
+
+    void add(PassRefPtr<T> track)
+    {
+        ASSERT(track);
+        m_tracks.append(track.get());
+        scheduleTrackEvent(EventTypeNames::addtrack, track);
+    }
+
+    void remove(const String& id)
+    {
+        for (unsigned i = 0; i < m_tracks.size(); ++i) {
+            if (m_tracks[i]->id() != id)
+                continue;
+
+            m_tracks[i]->setMediaElement(0);
+            scheduleTrackEvent(EventTypeNames::removetrack, m_tracks[i]);
+            m_tracks.remove(i);
+            return;
+        }
+    }
+
+    void removeAll()
+    {
+        for (unsigned i = 0; i < m_tracks.size(); ++i)
+            m_tracks[i]->setMediaElement(0);
+
+        m_tracks.clear();
+    }
+
+    void scheduleChangeEvent()
+    {
+        EventInit initializer;
+        initializer.bubbles = false;
+        initializer.cancelable = false;
+        RefPtr<Event> event = Event::create(EventTypeNames::change, initializer);
+        event->setTarget(this);
+        m_mediaElement->scheduleEvent(event);

[philipj_slow, 2014/03/28 08:27:15]

This isn't per spec but I think it should be:
https://www.w3.org/Bugs/Public/show_bug.cgi?id=25188

+    }
+
+private:
+    void scheduleTrackEvent(const AtomicString& eventName, PassRefPtr<T> track)
+    {
+        TrackEventInit initializer;
+        initializer.track = track;
+        initializer.bubbles = false;
+        initializer.cancelable = false;
+        RefPtr<Event> event = TrackEvent::create(eventName, initializer);
+        event->setTarget(this);
+        m_mediaElement->scheduleEvent(event);
+    }
+
+
+    Vector<RefPtr<T> > m_tracks;
+    HTMLMediaElement* m_mediaElement;
+};
+
+}
+
+#endif