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

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

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999-2001 Lars Knoll <knoll@kde.org>
  *                     1999-2001 Antti Koivisto <koivisto@kde.org>
  *                     2000-2001 Simon Hausmann <hausmann@kde.org>
  *                     2000-2001 Dirk Mueller <mueller@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
@@ skipping 50 matching lines @@
 
 // Frame is the base class of LocalFrame and RemoteFrame and should only contain
 // functionality shared between both. In particular, any method related to
 // input, layout, or painting probably belongs on LocalFrame.
 class CORE_EXPORT Frame : public GarbageCollectedFinalized<Frame> {
 public:
     virtual ~Frame();
 
     DECLARE_VIRTUAL_TRACE();
 
-    virtual bool isLocalFrame() const { return false; }
-    virtual bool isRemoteFrame() const { return false; }
+    virtual bool isLocalFrame() const = 0;
+    virtual bool isRemoteFrame() const = 0;
 
     virtual DOMWindow* domWindow() const = 0;
     virtual WindowProxy* windowProxy(DOMWrapperWorld&) = 0;
 
     virtual void navigate(Document& originDocument, const KURL&, bool replaceCurrentItem, UserGestureStatus) = 0;
     // This version of Frame::navigate assumes the resulting navigation is not
     // to be started on a timer. Use the method above in such cases.
     virtual void navigate(const FrameLoadRequest&) = 0;
     virtual void reload(FrameLoadType, ClientRedirectPolicy) = 0;
 
@@ skipping 82 matching lines @@
 {
     return m_treeNode;
 }
 
 // Allow equality comparisons of Frames by reference or pointer, interchangeably.
 DEFINE_COMPARISON_OPERATORS_WITH_REFERENCES_REFCOUNTED(Frame)
 
 } // namespace blink
 
 #endif // Frame_h