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

third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 56 matching lines @@
         STACK_ALLOCATED();
     public:
         UpdateSuspendScope();
         ~UpdateSuspendScope();
 
     private:
         void performDeferredWidgetTreeOperations();
     };
 
     // FrameOwner overrides:
-    bool isLocal() const override { return true; }
-    bool isRemote() const override { return false; }
     void setContentFrame(Frame&) override;
     void clearContentFrame() override;
     void dispatchLoad() override;
     SandboxFlags getSandboxFlags() const override { return m_sandboxFlags; }
     void renderFallbackContent() override { }
     ScrollbarMode scrollingMode() const override { return ScrollbarAuto; }
     int marginWidth() const override { return -1; }
     int marginHeight() const override { return -1; }
     bool allowFullscreen() const override { return false; }
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     HTMLFrameOwnerElement(const QualifiedName& tagName, Document&);
     void setSandboxFlags(SandboxFlags);
 
     bool loadOrRedirectSubframe(const KURL&, const AtomicString& frameName, bool replaceCurrentItem);
 
 private:
+    // Intentionally private to prevent redundant checks when the type is
+    // already HTMLFrameOwnerElement.
+    bool isLocal() const override { return true; }
+    bool isRemote() const override { return false; }
+
     bool isKeyboardFocusable() const override;
     bool isFrameOwnerElement() const final { return true; }
 
     virtual ReferrerPolicy referrerPolicyAttribute() { return ReferrerPolicyDefault; }
 
     Member<Frame> m_contentFrame;
     Member<Widget> m_widget;
     SandboxFlags m_sandboxFlags;
 };
 
@@ skipping 32 matching lines @@
     CORE_EXPORT static HeapHashCountedSet<Member<Node>>& disabledSubtreeRoots();
 
     Member<Node> m_root;
 };
 
 DEFINE_TYPE_CASTS(HTMLFrameOwnerElement, FrameOwner, owner, owner->isLocal(), owner.isLocal());
 
 } // namespace blink
 
 #endif // HTMLFrameOwnerElement_h