Add <link rel=preconnect> crossorigin attribute (take 2)

Source/core/loader/LinkHeader.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 LinkHeader_h
 #define LinkHeader_h
 
 #include "core/CoreExport.h"
+#include "core/html/CrossOriginAttribute.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class LinkHeader {
 public:
     template <typename CharType>
     LinkHeader(CharType*& position, CharType* end);
 
     const String url() const { return m_url; };
     const String rel() const { return m_rel; };
+    CrossOriginAttributeValue crossOrigin() const { return m_crossOrigin; }
     bool valid() const { return m_isValid; };
 
     enum LinkParameterName {
         LinkParameterUnknown,
         LinkParameterRel,
         LinkParameterAnchor,
+        LinkParameterCrossOrigin,
     };
 
 private:
     void setValue(LinkParameterName, String value);
 
     String m_url;
     String m_rel;
+    CrossOriginAttributeValue m_crossOrigin;
     bool m_isValid;
 };
 
 class CORE_EXPORT LinkHeaderSet {
 public:
     LinkHeaderSet(const String& header);
 
     Vector<LinkHeader>::const_iterator begin() const { return m_headerSet.begin(); }
     Vector<LinkHeader>::const_iterator end() const { return m_headerSet.end(); }
     LinkHeader& operator[](size_t i) { return m_headerSet[i]; }
     size_t size() { return m_headerSet.size(); }
 
 private:
     template <typename CharType>
     void init(CharType* headerValue, unsigned len);
 
     Vector<LinkHeader> m_headerSet;
 };
 
 }
 
 #endif