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

Source/core/html/track/AudioTrackList.cpp

+// 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.
+
+#include "config.h"
+#include "core/html/track/AudioTrackList.h"
+
+#include "core/html/HTMLMediaElement.h"
+#include "core/html/track/AudioTrack.h"
+
+namespace WebCore {
+
+PassRefPtrWillBeRawPtr<AudioTrackList> AudioTrackList::create(HTMLMediaElement* mediaElement)
+{
+    RefPtrWillBeRawPtr<AudioTrackList> trackList(adoptRefWillBeRefCountedGarbageCollected(new AudioTrackList(mediaElement)));
+    trackList->suspendIfNeeded();

[philipj_slow, 2014/03/09 09:04:14]

Does TextTrackList::create need this as well? If the track lists were made plain
members of HTMLMediaElement, I guess this won't be needed anywhere, unless it's
somehow possible to create an element in a state where ActiveDOMObject should be
suspended, which would be weird.

[acolwell GONE FROM CHROMIUM, 2014/03/18 22:02:15]

This is only needed because the XXTrackLists are ActiveDOMObjects. TextTrackList
isn't an ActiveDOMObject. This will likely go away given that AudioTrackList &
VideoTrackList are only ActiveDOMObjects because of the event queue, which will
be going away.

[philipj_slow, 2014/03/20 16:17:39]

Yep, it's gone now. (Commenting to tell which issues are still unresolved, sorry
for the spam.)

+    return trackList.release();
+}
+
+AudioTrackList::~AudioTrackList()
+{
+}
+
+AudioTrackList::AudioTrackList(HTMLMediaElement* mediaElement)
+    : TrackBaseList(mediaElement)
+{
+    ScriptWrappable::init(this);
+}
+
+AudioTrack* AudioTrackList::anonymousIndexedGetter(unsigned index) const
+{
+    return static_cast<AudioTrack*>(getByIndex(index));
+}
+
+AudioTrack* AudioTrackList::getTrackById(const AtomicString& id) const
+{
+    return static_cast<AudioTrack*>(getById(id));
+}
+
+bool AudioTrackList::hasEnabledTrack() const
+{
+    for (unsigned i = 0; i < length(); ++i) {
+        if (anonymousIndexedGetter(i)->enabled())
+            return true;
+    }
+
+    return false;
+}
+
+const AtomicString& AudioTrackList::interfaceName() const
+{
+    return EventTargetNames::AudioTrackList;
+}
+
+}