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

net/base/parse_data_url_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 "net/base/data_url.h"
+#include "url/gurl.h"
+
+// Entry point for LibFuzzer.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  std::string input(data, data + size);
+  std::string mime_type;
+  std::string charset;
+  std::string urldata;
+  net::DataURL::Parse(GURL(input), &mime_type, &charset, &urldata);
+  return 0;
+}