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

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 5a1ab2d7f1c2e118bde314d677a5b9d70b2b57a7..03aa98e6e2885e8a1054e2b5473c95c4f2a88af8 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -49,6 +49,7 @@ namespace WebCore {
 class AudioSourceProvider;
 class MediaElementAudioSourceNode;
 #endif
+class AudioTrackList;
 class ContentType;
 class Event;
 class ExceptionState;
@@ -62,6 +63,7 @@ class HTMLMediaSource;
 class TextTrackList;
 class TimeRanges;
 class URLRegistry;
+class VideoTrackList;
 
 typedef PODIntervalTree<double, TextTrackCue*> CueIntervalTree;
 typedef CueIntervalTree::IntervalType CueInterval;
@@ -163,6 +165,12 @@ public:
 
     virtual bool canPlay() const OVERRIDE FINAL;
 
+    AudioTrackList& audioTracks();
+    void audioTrackChanged(const AtomicString& audioTrackID, bool enabled);
+
+    VideoTrackList& videoTracks();
+    void selectedVideoTrackChanged(const AtomicString& selectedTrackID);
+
     PassRefPtr<TextTrack> addTextTrack(const AtomicString& kind, const AtomicString& label, const AtomicString& language, ExceptionState&);
     PassRefPtr<TextTrack> addTextTrack(const AtomicString& kind, const AtomicString& label, ExceptionState& exceptionState) { return addTextTrack(kind, label, emptyAtom, exceptionState); }
     PassRefPtr<TextTrack> addTextTrack(const AtomicString& kind, ExceptionState& exceptionState) { return addTextTrack(kind, emptyAtom, emptyAtom, exceptionState); }
@@ -181,6 +189,11 @@ public:
     void didAddTrackElement(HTMLTrackElement*);
     void didRemoveTrackElement(HTMLTrackElement*);
 
+    void addVideoTrack(const AtomicString& id, blink::WebMediaPlayerClient::VideoTrackKind, const AtomicString& label, const AtomicString& language, bool selected);
+    void removeVideoTrack(const AtomicString& id);
+    void addAudioTrack(const AtomicString& id, blink::WebMediaPlayerClient::AudioTrackKind, const AtomicString& label, const AtomicString& language, bool enabled);
+    void removeAudioTrack(const AtomicString& id);
+
     virtual void mediaPlayerDidAddTextTrack(blink::WebInbandTextTrack*) OVERRIDE FINAL;
     virtual void mediaPlayerDidRemoveTextTrack(blink::WebInbandTextTrack*) OVERRIDE FINAL;
     // FIXME: Remove this when WebMediaPlayerClientImpl::loadInternal does not depend on it.
@@ -413,6 +426,16 @@ private:
     bool isBlockedOnMediaController() const;
     bool isAutoplaying() const { return m_autoplaying; }
 
+    // Creates placeholder AudioTrack and/or VideoTrack objects when WebMemediaPlayer objects
+    // advertise they have audio and/or video, but don't explicity signal them via
+    // mediaPlayerDidAddAudioTrack() and mediaPlayerDidAddVideoTrack().
+    // FIXME: Remove this once all WebMediaPlayer implementations properly report their track info.
+    void createPlaceholderTracksIfNecessary();
+
+    // Sets the selected/enabled tracks if they aren't set before we initially
+    // transition to HAVE_METADATA.
+    void selectInitialTracksIfNecessary();
+
     Timer<HTMLMediaElement> m_loadTimer;
     Timer<HTMLMediaElement> m_progressEventTimer;
     Timer<HTMLMediaElement> m_playbackProgressTimer;
@@ -497,6 +520,8 @@ private:
     bool m_processingPreferenceChange : 1;
     double m_lastTextTrackUpdateTime;
 
+    RefPtr<AudioTrackList> m_audioTracks;

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

I realize you're following the existing style, but I can't see a good reason why
this can't just be "AudioTrackList m_audioTracks". The track lists are always
going to be created if a resource load, and allocating the memory for them as
part of HTMLMediaElement seems slightly better than having separate allocations.
More importantly, it lets you remove some null checks and makes the ownership
and non-nullness very clear. I tried the change locally and it compiled at
least. It's up to you how much you want to do in this review, of course.

[philipj_slow, 2014/03/09 16:26:43]

On second though my suggestion doesn't make sense because TrackBaseList is
refcounted and could outlive HTMLMediaElement. One could still create these in
the constructor to avoid some null checks, but I don't think it matters much.

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

I moved the list creation to the constructor since I don't see much of a win to
avoid creating them up front.

+    RefPtr<VideoTrackList> m_videoTracks;
     RefPtr<TextTrackList> m_textTracks;
     Vector<RefPtr<TextTrack> > m_textTracksWhenResourceSelectionBegan;