Issue FrameDestructionObserver::frameDestroyed() notification on detach.

Source/core/frame/LocalDOMWindow.h

Index: Source/core/frame/LocalDOMWindow.h
diff --git a/Source/core/frame/LocalDOMWindow.h b/Source/core/frame/LocalDOMWindow.h
index 2fb620b375190ccffc4c49f45dbedfd1740b48b8..9e5ac83f20253a4b0063e313b76c66b039110e26 100644
--- a/Source/core/frame/LocalDOMWindow.h
+++ b/Source/core/frame/LocalDOMWindow.h
@@ -242,6 +242,7 @@ private:
 
         // FrameDestructionObserver overrides:
         void willDetachFrameHost() override;
+        void frameDestroyed() override;
 
         RawPtrWillBeMember<LocalDOMWindow> m_window;
     };
@@ -265,6 +266,7 @@ private:
     };
 
     void willDetachFrameHost();
+    void frameDestroyed();
     void removeAllEventListenersInternal(BroadcastListenerRemoval);
 
     OwnPtrWillBeMember<WindowFrameObserver> m_frameObserver;