Add fuzzer for ParseURLHostnameToAddress to //net.

net/base/parse_url_hostname_to_address_fuzzer.cc

+// 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.
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <functional>
+
+#include "net/base/address_list.h"
+#include "net/base/ip_address.h"
+
+// Entry point for LibFuzzer.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  const base::StringPiece hostname(reinterpret_cast<const char*>(data), size);
+  net::IPAddress address;
+
+  if (net::ParseURLHostnameToAddress(hostname, &address)) {
+    // To fuzz port number without spending raw bytes of data, use hash(data).
+    std::size_t data_hash = std::hash<std::string>()(hostname.as_string());
+    uint16_t port = static_cast<uint16_t>(data_hash & 0xFFFF);
+    net::AddressList addresses =
+        net::AddressList::CreateFromIPAddress(address, port);
+
+    for (const auto& endpoint : addresses) {
+      endpoint.ToString();
+    }
+  }
+
+  return 0;
+}