Apply meta tag referrer policy for preloaded requests

Source/core/html/parser/ResourcePreloader.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 ResourcePreloader_h
 #define ResourcePreloader_h
 
 #include "core/CoreExport.h"
 #include "core/html/parser/PreloadRequest.h"
 
 namespace blink {
 
 class CORE_EXPORT ResourcePreloader {
 public:
     virtual void takeAndPreload(PreloadRequestStream&);
+    virtual void preloadReferrerPolicy(const String& policy) = 0;
+
 private:
     virtual void preload(PassOwnPtr<PreloadRequest>) = 0;
 };
 
 }
 
 #endif