Oilpan: prefer eager finalization over prefinalizers.

Source/platform/speech/PlatformSpeechSynthesizer.h

 /*
  * Copyright (C) 2013 Apple Computer, 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 40 matching lines @@
     virtual void speakingErrorOccurred(PlatformSpeechSynthesisUtterance*) = 0;
     virtual void boundaryEventOccurred(PlatformSpeechSynthesisUtterance*, SpeechBoundary, unsigned charIndex) = 0;
     virtual void voicesDidChange() = 0;
 
 protected:
     virtual ~PlatformSpeechSynthesizerClient() { }
 };
 
 class PLATFORM_EXPORT PlatformSpeechSynthesizer : public GarbageCollectedFinalized<PlatformSpeechSynthesizer> {
     WTF_MAKE_NONCOPYABLE(PlatformSpeechSynthesizer);
-    USING_PRE_FINALIZER(PlatformSpeechSynthesizer, dispose);
 public:
     static PlatformSpeechSynthesizer* create(PlatformSpeechSynthesizerClient*);
 
     virtual ~PlatformSpeechSynthesizer();
-    void dispose();
 
     const HeapVector<Member<PlatformSpeechSynthesisVoice>>& voiceList() const { return m_voiceList; }
     virtual void speak(PlatformSpeechSynthesisUtterance*);
     virtual void pause();
     virtual void resume();
     virtual void cancel();
 
     PlatformSpeechSynthesizerClient* client() const { return m_speechSynthesizerClient; }
 
     void setVoiceList(HeapVector<Member<PlatformSpeechSynthesisVoice>>&);
 
+    // Eager finalization is required to promptly release the owned WebSpeechSynthesizer.
+    //
+    // If not and delayed until lazily swept, m_webSpeechSynthesizerClient may end up
+    // being lazily swept first (i.e., before this PlatformSpeechSynthesizer), leaving
+    // m_webSpeechSynthesizer with a dangling pointer to a finalized object --
+    // WebSpeechSynthesizer embedder implementations calling notification methods in the
+    // other directions by way of m_webSpeechSynthesizerClient. Eagerly releasing
+    // WebSpeechSynthesizer prevents such unsafe accesses.
+    EAGERLY_FINALIZE();
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     explicit PlatformSpeechSynthesizer(PlatformSpeechSynthesizerClient*);
 
     virtual void initializeVoiceList();
 
     HeapVector<Member<PlatformSpeechSynthesisVoice>> m_voiceList;
 
 private:
     Member<PlatformSpeechSynthesizerClient> m_speechSynthesizerClient;
 
     OwnPtr<WebSpeechSynthesizer> m_webSpeechSynthesizer;
     Member<WebSpeechSynthesizerClientImpl> m_webSpeechSynthesizerClient;
 };
 
 } // namespace blink
 
 #endif // PlatformSpeechSynthesizer_h