Oilpan: Replace EAGERLY_FINALIZE in EventTarget's hierarchy with pre-finalizers

third_party/WebKit/Source/modules/mediastream/RTCDataChannel.cpp

 /*
  * Copyright (C) 2012 Google 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 57 matching lines @@
 }
 
 RTCDataChannel::RTCDataChannel(ExecutionContext* context, PassOwnPtr<WebRTCDataChannelHandler> handler)
     : m_executionContext(context)
     , m_handler(handler)
     , m_readyState(ReadyStateConnecting)
     , m_binaryType(BinaryTypeArrayBuffer)
     , m_scheduledEventTimer(this, &RTCDataChannel::scheduledEventTimerFired)
     , m_bufferedAmountLowThreshold(0U)
 {
+    ThreadState::current()->registerPreFinalizer(this);
     m_handler->setClient(this);
 }
 
 RTCDataChannel::~RTCDataChannel()
 {
-    // Notify the client that the channel is gone.
-    m_handler->setClient(0);
+}
+
+void RTCDataChannel::dispose()
+{
+    // Promptly clears a raw reference from content/ to an on-heap object
+    // so that content/ doesn't access it in a lazy sweeping phase.
+    m_handler->setClient(nullptr);
+    m_handler.clear();
 }
 
 RTCDataChannel::ReadyState RTCDataChannel::getHandlerState() const
 {
     return m_handler->state();
 }
 
 String RTCDataChannel::label() const
 {
     return m_handler->label();
@@ skipping 220 matching lines @@
 }
 
 DEFINE_TRACE(RTCDataChannel)
 {
     visitor->trace(m_executionContext);
     visitor->trace(m_scheduledEvents);
     RefCountedGarbageCollectedEventTargetWithInlineData<RTCDataChannel>::trace(visitor);
 }
 
 } // namespace blink