Disallow local/remote checks on subclasses of Frame, FrameOwner and DOMWindow.

third_party/WebKit/Source/core/frame/LocalDOMWindow.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 68 matching lines @@
     DECLARE_VIRTUAL_TRACE();
 
     Document* installNewDocument(const String& mimeType, const DocumentInit&, bool forceXHTML = false);
 
     // EventTarget overrides:
     ExecutionContext* getExecutionContext() const override;
     const LocalDOMWindow* toLocalDOMWindow() const override;
     LocalDOMWindow* toLocalDOMWindow() override;
 
     // DOMWindow overrides:
-    bool isLocalDOMWindow() const override { return true; }
     LocalFrame* frame() const override;
     Screen* screen() const override;
     History* history() const override;
     BarProp* locationbar() const override;
     BarProp* menubar() const override;
     BarProp* personalbar() const override;
     BarProp* scrollbars() const override;
     BarProp* statusbar() const override;
     BarProp* toolbar() const override;
     Navigator* navigator() const override;
@@ skipping 104 matching lines @@
     // EventTarget overrides.
     void addedEventListener(const AtomicString& eventType, RegisteredEventListener&) override;
     void removedEventListener(const AtomicString& eventType, const RegisteredEventListener&) override;
 
     // Protected DOMWindow overrides.
     void schedulePostMessage(MessageEvent*, PassRefPtr<SecurityOrigin> target, Document* source) override;
 
 private:
     class WindowFrameObserver;
 
+    // Intentionally private to prevent redundant checks when the type is
+    // already LocalDOMWindow.
+    bool isLocalDOMWindow() const override { return true; }
+    using DOMWindow::isRemoteDOMWindow;

[esprehn, 2016/05/26 20:36:45]

can we just write return false here?

[dcheng, 2016/05/26 20:45:32]

Done.

+
     explicit LocalDOMWindow(LocalFrame&);
     void dispose();
 
     void dispatchLoadEvent();
     void clearDocument();
     void willDestroyDocumentInFrame();
 
     void willDetachFrameHost();
     void frameDestroyed();
 
@@ skipping 35 matching lines @@
 }
 
 inline String LocalDOMWindow::defaultStatus() const
 {
     return m_defaultStatus;
 }
 
 } // namespace blink
 
 #endif // LocalDOMWindow_h