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

third_party/WebKit/Source/web/RemoteFrameOwner.h

 // Copyright 2015 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 RemoteFrameOwner_h
 #define RemoteFrameOwner_h
 
 #include "core/frame/FrameOwner.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "public/web/WebFrameOwnerProperties.h"
 
 namespace blink {
 
 // Helper class to bridge communication for a frame with a remote parent.
 // Currently, it serves two purposes:
 // 1. Allows the local frame's loader to retrieve sandbox flags associated with
 //    its owner element in another process.
 // 2. Trigger a load event on its owner element once it finishes a load.
 class RemoteFrameOwner final : public GarbageCollectedFinalized<RemoteFrameOwner>, public FrameOwner {
     USING_GARBAGE_COLLECTED_MIXIN(RemoteFrameOwner);
 public:
     static RemoteFrameOwner* create(SandboxFlags flags, const WebFrameOwnerProperties& frameOwnerProperties)
     {
         return new RemoteFrameOwner(flags, frameOwnerProperties);
     }
 
     // FrameOwner overrides:
-    bool isLocal() const override { return false; }
-    bool isRemote() const override { return true; }
     void setContentFrame(Frame&) override;
     void clearContentFrame() override;
     SandboxFlags getSandboxFlags() const override { return m_sandboxFlags; }
     void setSandboxFlags(SandboxFlags flags) { m_sandboxFlags = flags; }
     void dispatchLoad() override;
     // TODO(dcheng): Implement.
     void renderFallbackContent() override { }
     ScrollbarMode scrollingMode() const override { return m_scrolling; }
     int marginWidth() const override { return m_marginWidth; }
     int marginHeight() const override { return m_marginHeight; }
     bool allowFullscreen() const override { return m_allowFullscreen; }
 
     void setScrollingMode(WebFrameOwnerProperties::ScrollingMode);
     void setMarginWidth(int marginWidth) { m_marginWidth = marginWidth; }
     void setMarginHeight(int marginHeight) { m_marginHeight = marginHeight; }
     void setAllowFullscreen(bool allowFullscreen) { m_allowFullscreen = allowFullscreen; }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     RemoteFrameOwner(SandboxFlags, const WebFrameOwnerProperties&);
 
+    // Intentionally private to prevent redundant checks when the type is
+    // already HTMLFrameOwnerElement.
+    bool isLocal() const override { return false; }
+    bool isRemote() const override { return true; }
+
     Member<Frame> m_frame;
     SandboxFlags m_sandboxFlags;
     ScrollbarMode m_scrolling;
     int m_marginWidth;
     int m_marginHeight;
     bool m_allowFullscreen;
 };
 
 DEFINE_TYPE_CASTS(RemoteFrameOwner, FrameOwner, owner, owner->isRemote(), owner.isRemote());
 
 } // namespace blink
 
 #endif // RemoteFrameOwner_h