NetworkStateNotifier: also remove NetworkStateObserver in finalizer too

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
@@ skipping 388 matching lines @@
 }
 
 static void recordLoadReasonToHistogram(WouldLoadReason reason) {
   DEFINE_STATIC_LOCAL(
       EnumerationHistogram, unseenFrameHistogram,
       ("Navigation.DeferredDocumentLoading.StatesV3", WouldLoadReasonEnd));
   unseenFrameHistogram.count(reason);
 }
 
 class Document::NetworkStateObserver final
-    : public GarbageCollected<Document::NetworkStateObserver>,
+    : public GarbageCollectedFinalized<Document::NetworkStateObserver>,
       public NetworkStateNotifier::NetworkStateObserver,
       public ContextLifecycleObserver {
   USING_GARBAGE_COLLECTED_MIXIN(Document::NetworkStateObserver);
 
  public:
   explicit NetworkStateObserver(Document& document)
       : ContextLifecycleObserver(&document) {
     networkStateNotifier().addOnLineObserver(
         this,
         TaskRunnerHelper::get(TaskType::Networking, getExecutionContext()));
   }
 
+  ~NetworkStateObserver() {
+    if (getExecutionContext())

[sof, 2017/02/24 14:21:59]

It's safe to do this eagerly, but how about introducing

 void unregisterAsObserver(ExecutionContext* context) {
   if (!context)
     return;
   ...
 }

or something similarly named, which we then call from both the dtor and
contextDestroyed()?

It's just shifting lines of code around, but calling contextDestroyed() is
preferably left (only) for the LifecycleNotifier to do.

[kinuko, 2017/02/24 14:43:16]

Sounds good, done.

+      contextDestroyed(getExecutionContext());
+  }
+
   void onLineStateChange(bool onLine) override {
     AtomicString eventName =
         onLine ? EventTypeNames::online : EventTypeNames::offline;
     Document* document = toDocument(getExecutionContext());
     if (!document->domWindow())
       return;
     document->domWindow()->dispatchEvent(Event::create(eventName));
     InspectorInstrumentation::networkStateChanged(document->frame(), onLine);
   }
 
   void contextDestroyed(ExecutionContext* context) override {
     networkStateNotifier().removeOnLineObserver(
         this, TaskRunnerHelper::get(TaskType::Networking, context));
   }
 
   DEFINE_INLINE_VIRTUAL_TRACE() { ContextLifecycleObserver::trace(visitor); }
+  EAGERLY_FINALIZE();
 };
 
 Document::Document(const DocumentInit& initializer,
                    DocumentClassFlags documentClasses)
     : ContainerNode(0, CreateDocument),
       TreeScope(*this),
       m_hasNodesWithPlaceholderStyle(false),
       m_evaluateMediaQueriesOnStyleRecalc(false),
       m_pendingSheetLayout(NoLayoutWithPendingSheets),
       m_frame(initializer.frame()),
@@ skipping 6204 matching lines @@
 }
 
 void showLiveDocumentInstances() {
   WeakDocumentSet& set = liveDocumentSet();
   fprintf(stderr, "There are %u documents currently alive:\n", set.size());
   for (blink::Document* document : set)
     fprintf(stderr, "- Document %p URL: %s\n", document,
             document->url().getString().utf8().data());
 }
 #endif