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 34 matching lines @@
 namespace blink {
 
 class Frame;
 class HTMLDocument;
 class SecurityOrigin;
 
 // WindowProxy represents all the per-global object state for a Frame that
 // persist between navigations.
 class WindowProxy final : public GarbageCollectedFinalized<WindowProxy> {
  public:
+  // A valid transition is from ContextUninitialized to ContextInitialized,
+  // and then ContextDetached. Other transitions are forbidden.
+  enum class Lifecycle {

[Yuki, 2017/01/06 12:56:56]

nit: We can move this into private: section?

+    ContextUninitialized,
+    ContextInitialized,
+    ContextDetached,
+  };
+
   static WindowProxy* create(v8::Isolate*, Frame*, DOMWrapperWorld&);
 
   ~WindowProxy();
   DECLARE_TRACE();
 
   v8::Local<v8::Context> contextIfInitialized() const {
     return m_scriptState ? m_scriptState->context() : v8::Local<v8::Context>();
   }
   ScriptState* getScriptState() const { return m_scriptState.get(); }
 
   // 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; }
@@ skipping 23 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