Oilpan: Prpare to move WorkerEventQueue to Oilpan heap.

Source/core/workers/WorkerEventQueue.cpp

Index: Source/core/workers/WorkerEventQueue.cpp
diff --git a/Source/core/workers/WorkerEventQueue.cpp b/Source/core/workers/WorkerEventQueue.cpp
index d657d5f39356c13f589922d2828f61b8e445819c..abef8ee11e5b2af71d89c4910b55f786931b532d 100644
--- a/Source/core/workers/WorkerEventQueue.cpp
+++ b/Source/core/workers/WorkerEventQueue.cpp
@@ -33,9 +33,9 @@
 
 namespace WebCore {
 
-PassOwnPtr<WorkerEventQueue> WorkerEventQueue::create(ExecutionContext* context)
+PassOwnPtrWillBeRawPtr<WorkerEventQueue> WorkerEventQueue::create(ExecutionContext* context)
 {
-    return adoptPtr(new WorkerEventQueue(context));
+    return adoptPtrWillBeNoop(new WorkerEventQueue(context));
 }
 
 WorkerEventQueue::WorkerEventQueue(ExecutionContext* context)
@@ -46,7 +46,14 @@ WorkerEventQueue::WorkerEventQueue(ExecutionContext* context)
 
 WorkerEventQueue::~WorkerEventQueue()
 {
+#if !ENABLE(OILPAN)
     close();

[haraken, 2014/05/30 12:10:41]

I'm not sure if you can remove close() from the destructor. If you don't call
it, task->cancel() is not called. Then the task is not unregistered from the
WorkerEventQueue, and thus it's possible that
m_eventQueue->removeEvent(m_event.get()) at line 81 is executed after the
WorkerEventQueue is destructed.

An ideal solution would be to move ExecutionContextTask (from which
EventDispatcherTask is derived) to the heap and use Members for
EventDispatcherTask::m_event and EventDispatcherTask::m_eventQueue. However, it
looks a bit hard to move ExecutionContextTask to the heap (probably only for me
who doesn't have much template knowledge).....

[tkent, 2014/05/30 13:47:58]

In this patch, I moved this |close()| callsite to WorkerGlobalScope::dispose
because we should not touch on-heap object in the destructor.

[haraken, 2014/05/30 14:00:56]

oh, I missed that. That makes sense.

+#endif
+}
+
+void WorkerEventQueue::trace(Visitor* visitor)
+{
+    visitor->trace(m_eventTaskMap);
 }
 
 class WorkerEventQueue::EventDispatcherTask : public ExecutionContextTask {