Prevent 'removetrack' events from firing when all inband text tracks are removed.

Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 640 matching lines @@
     // a task to fire a simple event named abort at the media element.
     if (m_networkState == NETWORK_LOADING || m_networkState == NETWORK_IDLE)
         scheduleEvent(EventTypeNames::abort);
 
     closeMediaSource();
 
     createMediaPlayer();
 
     // 4 - If the media element's networkState is not set to NETWORK_EMPTY, then run these substeps
     if (m_networkState != NETWORK_EMPTY) {
+        // 4.1 - Queue a task to fire a simple event named emptied at the media element.
+        scheduleEvent(EventTypeNames::emptied);
+
+        // 4.2 - If a fetching process is in progress for the media element, the user agent should stop it.
         m_networkState = NETWORK_EMPTY;
+
+        // 4.3 - Forget the media element's media-resource-specific tracks.
+        forgetResourceSpecificTracks();
+
+        // 4.4 - If readyState is not set to HAVE_NOTHING, then set it to that state.
         m_readyState = HAVE_NOTHING;
         m_readyStateMaximum = HAVE_NOTHING;
+
+        // 4.5 - If the paused attribute is false, then set it to true.
+        m_paused = true;
+
+        // 4.6 - If seeking is true, set it to false.
+        m_seeking = false;
+
+        // 4.7 - Set the current playback position to 0.
+        //       Set the official playback position to 0.
+        //       If this changed the official playback position, then queue a task to fire a simple event named timeupdate at the media element.
+        // FIXME: Add support for firing this event.
+
+        // 4.8 - Set the initial playback position to 0.
+        // FIXME: Make this less subtle. The position only becomes 0 because of the createMediaPlayer() call
+        // above.
         refreshCachedTime();
-        m_paused = true;
-        m_seeking = false;
         invalidateCachedTime();
-        scheduleEvent(EventTypeNames::emptied);
+
+        // 4.9 - Set the timeline offset to Not-a-Number (NaN).
+        // 4.10 - Update the duration attribute to Not-a-Number (NaN).
+
+
         updateMediaController();
         if (RuntimeEnabledFeatures::videoTrackEnabled())
             updateActiveTextTrackCues(0);
     }
 
     // 5 - Set the playbackRate attribute to the value of the defaultPlaybackRate attribute.
     setPlaybackRate(defaultPlaybackRate());
 
     // 6 - Set the error attribute to null and the autoplaying flag to true.
     m_error = nullptr;
     m_autoplaying = true;
 
     // 7 - Invoke the media element's resource selection algorithm.
 
     // 8 - Note: Playback of any previously playing media resource for this element stops.
 
     // The resource selection algorithm
     // 1 - Set the networkState to NETWORK_NO_SOURCE
     m_networkState = NETWORK_NO_SOURCE;
 
     // 2 - Asynchronously await a stable state.
 
     m_playedTimeRanges = TimeRanges::create();
+
+    // FIXME: Investigate whether these can be moved into m_networkState != NETWORK_EMPTY block above
+    // so they are closer to the relevant spec steps.
     m_lastSeekTime = 0;
     m_duration = numeric_limits<double>::quiet_NaN();
 
     // The spec doesn't say to block the load event until we actually run the asynchronous section
     // algorithm, but do it now because we won't start that until after the timer fires and the
     // event may have already fired by then.
     setShouldDelayLoadEvent(true);
 
     configureMediaControls();
 }
@@ skipping 650 matching lines @@
 
     // 4.8.10.5
     // 6 - Reaching this step indicates that the media resource failed to load or that the given
     // URL could not be resolved. In one atomic operation, run the following steps:
 
     // 6.1 - Set the error attribute to a new MediaError object whose code attribute is set to
     // MEDIA_ERR_SRC_NOT_SUPPORTED.
     m_error = MediaError::create(MediaError::MEDIA_ERR_SRC_NOT_SUPPORTED);
 
     // 6.2 - Forget the media element's media-resource-specific text tracks.
+    forgetResourceSpecificTracks();
 
     // 6.3 - Set the element's networkState attribute to the NETWORK_NO_SOURCE value.
     m_networkState = NETWORK_NO_SOURCE;
 
     // 7 - Queue a task to fire a simple event named error at the media element.
     scheduleEvent(EventTypeNames::error);
 
     closeMediaSource();
 
     // 8 - Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
@@ skipping 54 matching lines @@
 }
 
 void HTMLMediaElement::mediaLoadingFailed(MediaPlayer::NetworkState error)
 {
     stopPeriodicTimers();
 
     // If we failed while trying to load a <source> element, the movie was never parsed, and there are more
     // <source> children, schedule the next one
     if (m_readyState < HAVE_METADATA && m_loadState == LoadingFromSourceElement) {
 
+        // resource selection algorithm
+        // Step 9.Otherwise.9 - Failed with elements: Queue a task, using the DOM manipulation task source, to fire a simple event named error at the candidate element.
         if (m_currentSourceNode)
             m_currentSourceNode->scheduleErrorEvent();
         else
             WTF_LOG(Media, "HTMLMediaElement::setNetworkState - error event not sent, <source> was removed");
 
+        // 9.Otherwise.10 - Asynchronously await a stable state. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended.
+
+        // 9.Otherwise.11 - Forget the media element's media-resource-specific tracks.
+        forgetResourceSpecificTracks();
+
         if (havePotentialSourceChild()) {
             WTF_LOG(Media, "HTMLMediaElement::setNetworkState - scheduling next <source>");
             scheduleNextSourceChild();
         } else {
             WTF_LOG(Media, "HTMLMediaElement::setNetworkState - no more <source> elements, waiting");
             waitForSourceChange();
         }
 
         return;
     }
@@ skipping 1038 matching lines @@
 
     if (!m_textTracks)
         return;
 
     // This cast is safe because we created the InbandTextTrack with the WebInbandTextTrack
     // passed to mediaPlayerDidAddTextTrack.
     RefPtr<InbandTextTrack> textTrack = static_cast<InbandTextTrack*>(webTrack->client());
     if (!textTrack)
         return;
 
-    removeTextTrack(textTrack.get());
+    removeTextTrack(textTrack.get(), true);
 }
 
 void HTMLMediaElement::closeCaptionTracksChanged()
 {
     if (hasMediaControls())
         mediaControls()->closedCaptionTracksChanged();
 }
 
 void HTMLMediaElement::addTextTrack(TextTrack* track)
 {
     textTracks()->append(track);
 
     closeCaptionTracksChanged();
 }
 
-void HTMLMediaElement::removeTextTrack(TextTrack* track)
+void HTMLMediaElement::removeTextTrack(TextTrack* track, bool scheduleEvent)
 {
     TrackDisplayUpdateScope scope(this);
     TextTrackCueList* cues = track->cues();
     if (cues)
         textTrackRemoveCues(track, cues);
-    m_textTracks->remove(track);
+    m_textTracks->remove(track, scheduleEvent);
 
     closeCaptionTracksChanged();
 }
 
-void HTMLMediaElement::removeAllInbandTracks()
+void HTMLMediaElement::forgetResourceSpecificTracks()
 {
-    if (!m_textTracks)
-        return;
+    if (m_textTracks) {
+        TrackDisplayUpdateScope scope(this);
+        for (int i = m_textTracks->length() - 1; i >= 0; --i) {

[adamk, 2014/02/26 00:45:32]

length() - 1 is scary since that's an unsigned. Are we sure that
m_textTracks.length() > 0 here? I guess that hasn't changed, but it'd be good to
at least add an ASSERT before this loop.

+            TextTrack* track = m_textTracks->item(i);
 
-    TrackDisplayUpdateScope scope(this);
-    for (int i = m_textTracks->length() - 1; i >= 0; --i) {
-        TextTrack* track = m_textTracks->item(i);
-
-        if (track->trackType() == TextTrack::InBand)
-            removeTextTrack(track);
+            if (track->trackType() == TextTrack::InBand)
+                removeTextTrack(track, false);
+        }
     }
 }
 
 PassRefPtr<TextTrack> HTMLMediaElement::addTextTrack(const AtomicString& kind, const AtomicString& label, const AtomicString& language, ExceptionState& exceptionState)
 {
     ASSERT(RuntimeEnabledFeatures::videoTrackEnabled());
 
     // 4.8.10.12.4 Text track API
     // The addTextTrack(kind, label, language) method of media elements, when invoked, must run the following steps:
 
@@ skipping 82 matching lines @@
 
     textTrack->setHasBeenConfigured(false);
 
     if (!m_textTracks)
         return;
 
     // 4.8.10.12.3 Sourcing out-of-band text tracks
     // When a track element's parent element changes and the old parent was a media element,
     // then the user agent must remove the track element's corresponding text track from the
     // media element's list of text tracks.
-    removeTextTrack(textTrack.get());
+    removeTextTrack(textTrack.get(), true);
 
     size_t index = m_textTracksWhenResourceSelectionBegan.find(textTrack.get());
     if (index != kNotFound)
         m_textTracksWhenResourceSelectionBegan.remove(index);
 }
 
 static int textTrackLanguageSelectionScore(const TextTrack& track)
 {
     if (track.language().isEmpty())
         return 0;
@@ skipping 732 matching lines @@
     m_player.clear();
 
 #if ENABLE(WEB_AUDIO)
     if (m_audioSourceNode)
         m_audioSourceNode->unlock();
 #endif
 }
 
 void HTMLMediaElement::clearMediaPlayer(int flags)
 {
-    removeAllInbandTracks();
+    forgetResourceSpecificTracks();
 
     closeMediaSource();
 
     setMediaKeysInternal(0);
 
     clearMediaPlayerAndAudioSourceProviderClient();
 
     stopPeriodicTimers();
     m_loadTimer.stop();
 
@@ skipping 501 matching lines @@
 {
     m_mediaSource->setWebMediaSourceAndOpen(adoptPtr(webMediaSource));
 }
 
 bool HTMLMediaElement::isInteractiveContent() const
 {
     return fastHasAttribute(controlsAttr);
 }
 
 }