Add fuzzer for PRTime() from NSPR.

BUG=none

Review-Url: https://codereview.chromium.org/2346723002
Cr-Commit-Position: refs/heads/master@{#419255}

testing/libfuzzer/fuzzers/BUILD.gn

@@ -400,3 +400,14 @@ fuzzer_test("skia_pathop_fuzzer") {
     additional_configs = [ "//testing/libfuzzer:no_clusterfuzz" ]
   }
 }
+
+fuzzer_test("prtime_fuzzer") {
+  sources = [
+    "prtime_fuzzer.cc",
+  ]
+  deps = [
+    "//base",
+  ]
+  dict = "dicts/prtime.dict"
+  libfuzzer_options = [ "max_len=1024" ]
+}

testing/libfuzzer/fuzzers/dicts/prtime.dict

+"0"
+"1"
+"2"
+"3"
+"4"
+"5"
+"6"
+"7"
+"8"
+"9"
+" "
+# <tab>
+"\x09"
+":"
+"."
+"/"
+"-"
+"+"
+";"
+"("
+")"
+"["
+"]"
+"T"
+"Z"
+"AM"
+"PM"
+"Mon"
+"Tue"
+"Wed"
+"Thu"
+"Fri"
+"Sat"
+"Sun"
+"Jan"
+"Feb"
+"Mar"
+"Apr"
+"May"
+"Jun"
+"Jul"
+"Aug"
+"Sep"
+"Oct"
+"Nov"
+"Dec"
+"AST"
+"BST"
+"CDT"
+"CST"
+"EDT"
+"EET"
+"EST"
+"GMT"
+"JST"
+"MDT"
+"MET"
+"MST"
+"NST"
+"PDT"
+"PST"
+"GMT"

testing/libfuzzer/fuzzers/prtime_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/third_party/nspr/prtime.h"
+
+PRTime parsed_time;
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size < 1)
+    return 0;
+
+  const uint8_t selector = data[0];
+
+  // Using std::string instead of a (potentially faster) fixed buffer to catch
+  // accesses beyond the end of the string.
+  std::string str(reinterpret_cast<const char*>(data+1), size - 1);
+  PR_ParseTimeString(str.c_str(), selector & 1, &parsed_time);
+
+  return 0;
+}