Add a Link header parser.

Source/core/loader/LinkHeader.h

Index: Source/core/loader/LinkHeader.h
diff --git a/Source/core/loader/LinkHeader.h b/Source/core/loader/LinkHeader.h
new file mode 100644
index 0000000000000000000000000000000000000000..e82a291c426267858e9c7ed681cda069969c41c7
--- /dev/null
+++ b/Source/core/loader/LinkHeader.h
@@ -0,0 +1,37 @@
+// 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 "wtf/text/WTFString.h"
+
+namespace blink {
+
+class LinkHeader {
+public:
+    LinkHeader(const String& header);
+
+    const String url() const { return m_url; };
+    const String rel() const { return m_rel; };
+    bool valid() const { return m_isValid; };
+
+    enum LinkParameterName {
+        LinkParameterUnknown,
+        LinkParameterRel,
+    };
+
+private:
+    template <typename CharType>
+    bool init(CharType* headerValue, unsigned len);
+    void setValue(LinkParameterName, String value);
+
+    String m_url;
+    String m_rel;
+    bool m_isValid;
+};
+
+}
+
+#endif