ScriptState::contextIsEmpty shouldn't return true for a context whose global object is detached

Source/bindings/core/v8/ScriptState.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ScriptState_h
 #define ScriptState_h
 
 #include "bindings/core/v8/ScopedPersistent.h"
 #include "bindings/core/v8/V8PerContextData.h"
 #include "wtf/RefCounted.h"
@@ skipping 56 matching lines @@
     static ScriptState* forMainWorld(LocalFrame*);
 
     v8::Isolate* isolate() const { return m_isolate; }
     DOMWrapperWorld& world() const { return *m_world; }
     LocalDOMWindow* domWindow() const;
     virtual ExecutionContext* executionContext() const;
     virtual void setExecutionContext(ExecutionContext*);
 
     // This can return an empty handle if the v8::Context is gone.
     v8::Handle<v8::Context> context() const { return m_context.newLocal(m_isolate); }
-    bool contextIsEmpty() const { return m_context.isEmpty(); }
+    bool contextIsValid() const { return m_context.isEmpty() || m_globalObjectDetached; }
+    void detachGlobalObject();
     void clearContext() { return m_context.clear(); }
 
     V8PerContextData* perContextData() const { return m_perContextData.get(); }
     void disposePerContextData() { m_perContextData = nullptr; }
 
     bool evalEnabled() const;
     void setEvalEnabled(bool);
     ScriptValue getFromGlobalObject(const char* name);
 
 protected:
     ScriptState(v8::Handle<v8::Context>, PassRefPtr<DOMWrapperWorld>);
 
 private:
     v8::Isolate* m_isolate;
     // This persistent handle is weak.
     ScopedPersistent<v8::Context> m_context;
 
     // This RefPtr doesn't cause a cycle because all persistent handles that DOMWrapperWorld holds are weak.
     RefPtr<DOMWrapperWorld> m_world;
 
     // This OwnPtr causes a cycle:
     // V8PerContextData --(Persistent)--> v8::Context --(RefPtr)--> ScriptState --(OwnPtr)--> V8PerContextData
     // So you must explicitly clear the OwnPtr by calling disposePerContextData()
     // once you no longer need V8PerContextData. Otherwise, the v8::Context will leak.
     OwnPtr<V8PerContextData> m_perContextData;
+
+    bool m_globalObjectDetached;
 };
 
 class ScriptStateForTesting : public ScriptState {
 public:
     static PassRefPtr<ScriptStateForTesting> create(v8::Handle<v8::Context>, PassRefPtr<DOMWrapperWorld>);
 
     virtual ExecutionContext* executionContext() const OVERRIDE;
     virtual void setExecutionContext(ExecutionContext*) OVERRIDE;
 
 private:
@@ skipping 23 matching lines @@
     }
 
 private:
     RefPtr<ScriptState> m_scriptState;
     ScopedPersistent<v8::Context> m_context;
 };
 
 }
 
 #endif // ScriptState_h