Push cue timeline management out of LoadableTextTrack

Source/core/html/track/TextTrack.h

Index: Source/core/html/track/TextTrack.h
diff --git a/Source/core/html/track/TextTrack.h b/Source/core/html/track/TextTrack.h
index 09f3d70212a1ba2fdae90098e7bdb76f6e47fc2d..eee03f8e4a72107e574f34ecc2860abb880fa711 100644
--- a/Source/core/html/track/TextTrack.h
+++ b/Source/core/html/track/TextTrack.h
@@ -125,16 +125,17 @@ protected:
     virtual bool isValidKind(const AtomicString& kind) const override { return isValidKindKeyword(kind); }
     virtual AtomicString defaultKind() const override { return subtitlesKeyword(); }
 
+    void addListOfCues(WillBeHeapVector<RefPtrWillBeMember<TextTrackCue>>&);
+
+private:
     CueTimeline* cueTimeline() const;
 
+    TextTrackCueList* ensureTextTrackCueList();
     RefPtrWillBeMember<TextTrackCueList> m_cues;
 
-private:
     VTTRegionList* ensureVTTRegionList();
     RefPtrWillBeMember<VTTRegionList> m_regions;
 
-    TextTrackCueList* ensureTextTrackCueList();
-
     RawPtrWillBeMember<TextTrackList> m_trackList;
     AtomicString m_mode;
     TextTrackType m_trackType;