Implement referrerpolicy attribute for img elements

Source/core/html/parser/PreloadRequest.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 PreloadRequest_h
 #define PreloadRequest_h
 
 #include "core/fetch/ClientHintsPreferences.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/Resource.h"
@@ skipping 29 matching lines @@
 
     Resource::Type resourceType() const { return m_resourceType; }
 
     const String& resourceURL() const { return m_resourceURL; }
     float resourceWidth() const { return m_resourceWidth.isSet ? m_resourceWidth.width : 0; }
     const KURL& baseURL() const { return m_baseURL; }
     bool isPreconnect() const { return m_requestType == RequestTypePreconnect; }
     bool isCORS() const { return m_isCORSEnabled; }
     bool isAllowCredentials() const { return m_allowCredentials == AllowStoredCredentials; }
     const ClientHintsPreferences& preferences() const { return m_clientHintsPreferences; }
+    ReferrerPolicy referrerPolicy() const { return m_referrerPolicy; }
 
 private:
     PreloadRequest(const String& initiatorName,
         const TextPosition& initiatorPosition,
         const String& resourceURL,
         const KURL& baseURL,
         Resource::Type resourceType,
         const FetchRequest::ResourceWidth& resourceWidth,
         const ClientHintsPreferences& clientHintsPreferences,
         RequestType requestType,
@@ skipping 30 matching lines @@
     ClientHintsPreferences m_clientHintsPreferences;
     RequestType m_requestType;
     ReferrerPolicy m_referrerPolicy;
 };
 
 typedef Vector<OwnPtr<PreloadRequest>> PreloadRequestStream;
 
 }
 
 #endif