Oilpan: Prepare to move EventQueue and its subclasses to Oilpan heap.

Source/core/html/track/TextTrackList.cpp

 /*
  * Copyright (C) 2011, 2012 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 29 matching lines @@
     : m_owner(owner)
     , m_asyncEventQueue(GenericEventQueue::create(this))
 {
     ScriptWrappable::init(this);
 }
 
 TextTrackList::~TextTrackList()
 {
 #if !ENABLE(OILPAN)
     ASSERT(!m_owner);
-#endif
+
+    // TextTrackList and m_asyncEventQueue always become unreachable
+    // together. So TextTrackList and m_asyncEventQueue are destructed in the
+    // same GC. We don't need to close it explicitly in Oilpan.
     m_asyncEventQueue->close();

[haraken, 2014/06/12 10:48:51]

In non-oilpan builds, some destructors call close(), some destructors call
cancelAllEvents(), and some destructors do nothing. I think we need to do
nothing, because destroying OwnPtr<EventQueue> will gracefully clean up the
EventQueue.

So I think you can just remove close() and cancelAllEvents() from these
destructors instead of moving them to #if !ENABLE(OILPAN). However, I'm OK with
your CL to keep the current non-oilpan code as is.

[tkent, 2014/06/12 23:50:12]

I'd like to keep non-oilpan code.

-#if !ENABLE(OILPAN)
+
     for (unsigned i = 0; i < length(); ++i) {
         item(i)->setTrackList(0);
     }
 #endif
 }
 
 unsigned TextTrackList::length() const
 {
     return m_addTrackTracks.size() + m_elementTracks.size() + m_inbandTracks.size();
 }
@@ skipping 264 matching lines @@
 }
 
 HTMLMediaElement* TextTrackList::owner() const
 {
     return m_owner;
 }
 
 void TextTrackList::trace(Visitor* visitor)
 {
     visitor->trace(m_owner);
+    visitor->trace(m_asyncEventQueue);
     visitor->trace(m_addTrackTracks);
     visitor->trace(m_elementTracks);
     visitor->trace(m_inbandTracks);
     EventTargetWithInlineData::trace(visitor);
 }