Oilpan: add transition types to track interface objects.

Source/core/html/track/TextTrack.cpp

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 82 matching lines @@
 {
     DEFINE_STATIC_LOCAL(const AtomicString, ended, ("showing", AtomicString::ConstructFromLiteral));
     return ended;
 }
 
 TextTrack::TextTrack(Document& document, const AtomicString& kind, const AtomicString& label, const AtomicString& language, const AtomicString& id, TextTrackType type)
     : TrackBase(TrackBase::TextTrack, label, language, id)
     , m_cues(nullptr)
     , m_regions(nullptr)
     , m_document(&document)
-    , m_trackList(0)
+    , m_trackList(nullptr)
     , m_mode(disabledKeyword())
     , m_trackType(type)
     , m_readinessState(NotLoaded)
     , m_trackIndex(invalidTrackIndex)
     , m_renderedTrackIndex(invalidTrackIndex)
     , m_hasBeenConfigured(false)
 {
     ScriptWrappable::init(this);
     setKind(kind);
 }
 
 TextTrack::~TextTrack()
 {
+#if !ENABLE(OILPAN)
     ASSERT(!m_trackList);
 
     if (m_cues) {
         for (size_t i = 0; i < m_cues->length(); ++i)
             m_cues->item(i)->setTrack(0);
     }
 
     if (m_regions) {
         for (size_t i = 0; i < m_regions->length(); ++i)
             m_regions->item(i)->setTrack(0);
     }

[haraken, 2014/04/21 01:30:54]

Actually I don't fully understand the relationship between TextTrack,
TextTrackCueList and VTTRegionList, and thus it's not clear to me if it's OK to
just comment out the setTrack(0)s from the destructor. Would you elaborate on it
for me?

[sof, 2014/04/21 15:23:42]

Cues and regions for a text track are explicitly added and removed from this
list. They maintain a strong reference back to their list, which is cleared when
they're explicitly remove()d.

Consequently, not clearing them is fine, as they'll be destructed together.

For similar reasons, m_trackList doesn't have to be checked for being empty or
not in the Oilpan case. If it is null, then the TextTrack has been removed from
a TextTrackList. If it is non-null, then the TextTrack object is being
finalized/destructed at the same time as its TextTrackList parent.

A TextTrackList persistent reference is kept by a media element. And as it
explicitly clears itself as an owner of the TextTrackList, by the time this
destructor (and that for TextTrackList) gets to run, the effect of calling e.g.
setTrack(0) is effectively a no-op, it has been detached from the media element
and won't cause any updates.

[haraken, 2014/04/22 02:37:47]

Thanks for the detailed explanation. You explanation makes sense, but does it
mean that we don't need the code (line 118 - 127) even in non-oilpan builds? If
TextTrackList and TextTracks in the list die together, we won't need to
explicitly call setTrack(0).

[sof, 2014/04/22 06:27:51]

That is a good observation. As the pointers in the reverse direction are just
raw pointers in the non-Oilpan case, clearing them out has no practical function
at this stage. And we're already letting go of the ref pointers in the other
direction to release the track & cue objects, so no further work needed here.

Removed these two loops + #if.

+#endif
 }
 
 bool TextTrack::isValidKindKeyword(const AtomicString& value)
 {
     if (value == subtitlesKeyword())
         return true;
     if (value == captionsKeyword())
         return true;
     if (value == descriptionsKeyword())
         return true;
@@ skipping 79 matching lines @@
     // then the activeCues attribute must return a live TextTrackCueList object ...
     // ... whose active flag was set when the script started, in text track cue
     // order. Otherwise, it must return null. When an object is returned, the
     // same object must be returned each time.
     // http://www.whatwg.org/specs/web-apps/current-work/#dom-texttrack-activecues
     if (m_cues && m_mode != disabledKeyword())
         return m_cues->activeCues();
     return 0;
 }
 
-void TextTrack::addCue(PassRefPtr<TextTrackCue> prpCue)
+void TextTrack::addCue(PassRefPtrWillBeRawPtr<TextTrackCue> prpCue)
 {
     if (!prpCue)
         return;
 
-    RefPtr<TextTrackCue> cue = prpCue;
+    RefPtrWillBeRawPtr<TextTrackCue> cue = prpCue;
 
     // TODO(93143): Add spec-compliant behavior for negative time values.
     if (std::isnan(cue->startTime()) || std::isnan(cue->endTime()) || cue->startTime() < 0 || cue->endTime() < 0)
         return;
 
     // 4.8.10.12.5 Text track API
 
     // The addCue(cue) method of TextTrack objects, when invoked, must run the following steps:
 
     // 1. If the given cue is in a text track list of cues, then remove cue from that text track
@@ skipping 51 matching lines @@
     // represents is not the text track disabled mode, then the regions
     // attribute must return a live VTTRegionList object that represents
     // the text track list of regions of the text track. Otherwise, it must
     // return null. When an object is returned, the same object must be returned
     // each time.
     if (RuntimeEnabledFeatures::webVTTRegionsEnabled() && m_mode != disabledKeyword())
         return ensureVTTRegionList();
     return 0;
 }
 
-void TextTrack::addRegion(PassRefPtr<VTTRegion> prpRegion)
+void TextTrack::addRegion(PassRefPtrWillBeRawPtr<VTTRegion> prpRegion)
 {
     if (!prpRegion)
         return;
 
-    RefPtr<VTTRegion> region = prpRegion;
+    RefPtrWillBeRawPtr<VTTRegion> region = prpRegion;
     VTTRegionList* regionList = ensureVTTRegionList();
 
     // 1. If the given region is in a text track list of regions, then remove
     // region from that text track list of regions.
     TextTrack* regionTrack = region->track();
     if (regionTrack && regionTrack != this)
         regionTrack->removeRegion(region.get(), ASSERT_NO_EXCEPTION);
 
     // 2. If the method's TextTrack object's text track list of regions contains
     // a region with the same identifier as region replace the values of that
@@ skipping 106 matching lines @@
 ExecutionContext* TextTrack::executionContext() const
 {
     return m_document;
 }
 
 HTMLMediaElement* TextTrack::mediaElement()
 {
     return m_trackList ? m_trackList->owner() : 0;
 }
 
+void TextTrack::trace(Visitor* visitor)
+{
+    visitor->trace(m_cues);
+    visitor->trace(m_regions);
+    visitor->trace(m_trackList);
+    TrackBase::trace(visitor);
+}
+
 } // namespace WebCore