Add fuzz testers to //net for some functions with simple parsing APIs.

net/base/registry_controlled_domains/get_domain_and_registry_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 "base/at_exit.h"
+#include "base/i18n/icu_util.h"
+#include "base/strings/string_piece.h"
+#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
+#include "url/gurl.h"
+
+// Initialize ICU.
+struct InitICU {
+  InitICU() { CHECK(base::i18n::InitializeICU()); }
+  base::AtExitManager at_exit_manager;
+};
+
+InitICU* init_icu = new InitICU();
+
+// Entry point for LibFuzzer.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  // Call GetDomainAndRegistry() twice - once with each filter type to ensure
+  // both code paths are exercised.
+  net::registry_controlled_domains::GetDomainAndRegistry(
+      base::StringPiece(reinterpret_cast<const char*>(data), size),
+      net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES);
+
+  net::registry_controlled_domains::GetDomainAndRegistry(
+      base::StringPiece(reinterpret_cast<const char*>(data), size),
+      net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
+
+  return 0;
+}