Introduce a lifecycle model to WindowProxy

third_party/WebKit/Source/bindings/core/v8/WindowProxy.h

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 54 matching lines @@
   // Update document object of the frame.
   void updateDocument();
 
   void namedItemAdded(HTMLDocument*, const AtomicString&);
   void namedItemRemoved(HTMLDocument*, const AtomicString&);
 
   // Update the security origin of a document
   // (e.g., after setting docoument.domain).
   void updateSecurityOrigin(SecurityOrigin*);
 
-  bool isContextInitialized() {
-    return m_scriptState && !!m_scriptState->perContextData();
-  }
   void initializeIfNeeded();
 
   void clearForNavigation();
   void clearForClose();
 
   v8::Local<v8::Object> globalIfNotDetached();
   v8::Local<v8::Object> releaseGlobal();
   void setGlobal(v8::Local<v8::Object>);
 
   DOMWrapperWorld& world() { return *m_world; }
 
  private:
+  // A valid transition is from ContextUninitialized to ContextInitialized,
+  // and then ContextDetached. Other transitions are forbidden.
+  enum class Lifecycle {
+    ContextUninitialized,
+    ContextInitialized,
+    ContextDetached,
+  };
+
   WindowProxy(Frame*, PassRefPtr<DOMWrapperWorld>, v8::Isolate*);
   void initialize();
 
   enum GlobalDetachmentBehavior { DoNotDetachGlobal, DetachGlobal };
   void disposeContext(GlobalDetachmentBehavior);
 
   void setSecurityToken(SecurityOrigin*);
 
   // The JavaScript wrapper for the document object is cached on the global
   // object for fast access. UpdateDocumentProperty sets the wrapper
@@ skipping 11 matching lines @@
 
   // Associates the window wrapper and its prototype chain with the native
   // DOMWindow object.  Also does some more Window-specific initialization.
   void setupWindowPrototypeChain();
 
   Member<Frame> m_frame;
   v8::Isolate* m_isolate;
   RefPtr<ScriptState> m_scriptState;
   RefPtr<DOMWrapperWorld> m_world;
   ScopedPersistent<v8::Object> m_globalProxy;
+  Lifecycle m_lifecycle;
 };
 
 }  // namespace blink
 
 #endif  // WindowProxy_h