NetworkStateNotifier: also remove NetworkStateObserver in finalizer too

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

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index b8178d8ac6d4d502ab047f41ed3a26978f8b2146..6f8ab0f87f4e8e94e805a7bfc0a84884ce534c3f 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -406,7 +406,7 @@ static void recordLoadReasonToHistogram(WouldLoadReason reason) {
 }
 
 class Document::NetworkStateObserver final
-    : public GarbageCollected<Document::NetworkStateObserver>,
+    : public GarbageCollectedFinalized<Document::NetworkStateObserver>,
       public NetworkStateNotifier::NetworkStateObserver,
       public ContextLifecycleObserver {
   USING_GARBAGE_COLLECTED_MIXIN(Document::NetworkStateObserver);
@@ -419,6 +419,11 @@ class Document::NetworkStateObserver final
         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;
@@ -435,6 +440,7 @@ class Document::NetworkStateObserver final
   }
 
   DEFINE_INLINE_VIRTUAL_TRACE() { ContextLifecycleObserver::trace(visitor); }
+  EAGERLY_FINALIZE();
 };
 
 Document::Document(const DocumentInit& initializer,