Implement referrerpolicy attr for iframes

Source/core/html/HTMLIFrameElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  * Copyright (C) 2004, 2006, 2008, 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef HTMLIFrameElement_h
 #define HTMLIFrameElement_h
 
 #include "core/dom/DOMSettableTokenList.h"
 #include "core/html/HTMLFrameElementBase.h"
+#include "platform/weborigin/SecurityPolicy.h"
 
 namespace blink {
 
 class HTMLIFrameElement final : public HTMLFrameElementBase, public DOMSettableTokenListObserver {
     DEFINE_WRAPPERTYPEINFO();
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLIFrameElement);
 public:
     DECLARE_NODE_FACTORY(HTMLIFrameElement);
     DECLARE_VIRTUAL_TRACE();
     ~HTMLIFrameElement() override;
@@ skipping 12 matching lines @@
 
     bool layoutObjectIsNeeded(const ComputedStyle&) override;
     LayoutObject* createLayoutObject(const ComputedStyle&) override;
 
     bool loadedNonEmptyDocument() const override { return m_didLoadNonEmptyDocument; }
     void didLoadNonEmptyDocument() override { m_didLoadNonEmptyDocument = true; }
     bool isInteractiveContent() const override;
 
     void valueChanged() override;
 
+    bool referrerPolicyAttribute(ReferrerPolicy*) override;
+
     AtomicString m_name;
     bool m_didLoadNonEmptyDocument;
     RefPtrWillBeMember<DOMSettableTokenList> m_sandbox;
+
+    ReferrerPolicy m_referrerPolicy;
 };
 
 } // namespace blink
 
 #endif // HTMLIFrameElement_h