Add simple HPKP and HSTS header parser fuzzers.

net/http/http_security_headers_hpkp_report_only_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 <string>
+
+#include "base/time/time.h"
+#include "net/http/http_security_headers.h"
+#include "url/gurl.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  std::string input(data, data + size);
+  bool include_subdomains;
+  net::HashValueVector spki_hashes;
+  GURL report_uri;
+  net::ParseHPKPReportOnlyHeader(input, &include_subdomains, &spki_hashes,
+                                 &report_uri);
+  return 0;
+}