Converting PlatformSpeechSynthesizer to PreFinalizer

Bug: 981043
Change-Id: I405ec5da96e34a5bf5665ea338130976614d8237
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1697188
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676589}

third_party/blink/renderer/platform/speech/platform_speech_synthesizer.cc

@@ -113,4 +113,8 @@ void PlatformSpeechSynthesizer::Trace(blink::Visitor* visitor) {
   visitor->Trace(web_speech_synthesizer_client_);
 }
 
+void PlatformSpeechSynthesizer::Dispose() {
+  web_speech_synthesizer_.reset();
+}
+
 }  // namespace blink

third_party/blink/renderer/platform/speech/platform_speech_synthesizer.h

@@ -62,6 +62,18 @@ class PLATFORM_EXPORT PlatformSpeechSynthesizerClient
 
 class PLATFORM_EXPORT PlatformSpeechSynthesizer
     : public GarbageCollectedFinalized<PlatformSpeechSynthesizer> {
+  // Pre-finalization is required to promptly release the owned
+  // WebSpeechSynthesizer.
+  //
+  // If not and delayed until lazily swept, web_speech_synthesizer_client_ may
+  // end up being lazily swept first (i.e., before this
+  // PlatformSpeechSynthesizer), leaving web_speech_synthesizer_ with a
+  // dangling pointer to a finalized object -- WebSpeechSynthesizer embedder
+  // implementations calling notification methods in the other directions by
+  // way of web_speech_synthesizer_client_. Eagerly releasing
+  // WebSpeechSynthesizer prevents such unsafe accesses.
+  USING_PRE_FINALIZER(PlatformSpeechSynthesizer, Dispose);
+
  public:
   static PlatformSpeechSynthesizer* Create(PlatformSpeechSynthesizerClient*);
 
@@ -81,19 +93,10 @@ class PLATFORM_EXPORT PlatformSpeechSynthesizer
 
   void SetVoiceList(Vector<scoped_refptr<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();
   virtual void Trace(blink::Visitor*);
 
+  void Dispose();
+
  protected:
   virtual void InitializeVoiceList();