Add fuzzer test for preg_parser

components/policy/core/common/preg_parser_fuzzer.cc

+// Copyright 2017 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 <base/strings/utf_string_conversions.h>
+#include "base/strings/string16.h"
+
+#include "components/policy/core/common/policy_load_status.h"
+#include "components/policy/core/common/preg_parser.h"
+#include "components/policy/core/common/registry_dict.h"
+
+namespace {
+
+const char kRegistryChromePolicyKey[] = "SOFTWARE\\Policies\\Chromium";
+
+}  // namespace
+
+namespace policy {
+namespace preg_parser {
+
+// Disable logging.
+struct Environment {
+  Environment() : root(base::ASCIIToUTF16(kRegistryChromePolicyKey)) {
+    logging::SetMinLogLevel(logging::LOG_FATAL);
+  }
+
+  const base::string16 root;
+};
+
+Environment* env = new Environment();
+
+// Entry point for LibFuzzer.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  RegistryDict dict;
+  PolicyLoadStatus status;
+  ReadDataInternal(data, size, env->root, &dict, &status, "data");
+  return 0;
+}
+
+}  // namespace preg_parser
+}  // namespace policy