Implement referrerpolicy attr for iframes

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
  * 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 HTMLFrameOwnerElement_h
 #define HTMLFrameOwnerElement_h
 
 #include "core/CoreExport.h"
 #include "core/dom/Document.h"
 #include "core/frame/FrameOwner.h"
 #include "core/html/HTMLElement.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollTypes.h"
+#include "platform/weborigin/SecurityPolicy.h"
 #include "wtf/HashCountedSet.h"
 
 namespace blink {
 
 class LocalDOMWindow;
 class ExceptionState;
 class Frame;
 class LayoutPart;
 class Widget;
 
@@ skipping 47 matching lines @@
 protected:
     HTMLFrameOwnerElement(const QualifiedName& tagName, Document&);
     void setSandboxFlags(SandboxFlags);
 
     bool loadOrRedirectSubframe(const KURL&, const AtomicString& frameName, bool replaceCurrentItem);
 
 private:
     bool isKeyboardFocusable() const override;
     bool isFrameOwnerElement() const final { return true; }
 
+    virtual ReferrerPolicy referrerPolicyAttribute() { return ReferrerPolicyDefault; }
+
     RawPtrWillBeMember<Frame> m_contentFrame;
     RefPtrWillBeMember<Widget> m_widget;
     SandboxFlags m_sandboxFlags;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(HTMLFrameOwnerElement, isFrameOwnerElement());
 
 class SubframeLoadingDisabler {
     STACK_ALLOCATED();
 public:
@@ skipping 23 matching lines @@
     static WillBeHeapHashCountedSet<RawPtrWillBeMember<Node>>& disabledSubtreeRoots();
 
     RawPtrWillBeMember<Node> m_root;
 };
 
 DEFINE_TYPE_CASTS(HTMLFrameOwnerElement, FrameOwner, owner, owner->isLocal(), owner.isLocal());
 
 } // namespace blink
 
 #endif // HTMLFrameOwnerElement_h