Share link header parsing code between blink and content.

components/link_header_util/link_header_util.h

+// Copyright 2016 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 COMPONENTS_LINK_HEADER_UTIL_LINK_HEADER_UTIL_H_
+#define COMPONENTS_LINK_HEADER_UTIL_LINK_HEADER_UTIL_H_
+
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/optional.h"
+
+namespace link_header_util {
+
+using StringIteratorPair =
+    std::pair<std::string::const_iterator, std::string::const_iterator>;
+
+std::vector<StringIteratorPair> SplitLinkHeader(const std::string& header);
+bool ParseLinkHeaderValue(
+    std::string::const_iterator begin,
+    std::string::const_iterator end,
+    std::string* url,
+    std::unordered_map<std::string, base::Optional<std::string>>* params);
+
+}  // namespace link_header_util
+
+#endif  // COMPONENTS_LINK_HEADER_UTIL_LINK_HEADER_UTIL_H_