Exercise *Rrdata::Create() functions in net_dns_record_fuzzer

This CL attempts to improve the fuzzer coverage of the various
Create() functions that are invoked by RecordParsed::CreateFrom(),
e.g. ARecordRdata::Create().  See [1] for fuzzer coverage prior to
this CL.

[1]: https://chromium-coverage.appspot.com/reports/699620_fuzzers_only/linux/chromium/src/net/dns/record_rdata.cc.html

Change-Id: Icad9ca987464f76099daf649d9f46f41c1c9ab9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829939
Commit-Queue: Dan McArdle <dmcardle@chromium.org>
Reviewed-by: Eric Orth <ericorth@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702856}

net/dns/dns_record_fuzzer.cc

@@ -5,9 +5,13 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include <memory>
+
 #include "base/files/file_path.h"
 #include "base/logging.h"
+#include "base/time/time.h"
 #include "net/dns/dns_response.h"
+#include "net/dns/record_parsed.h"
 
 void InitLogging() {
   // For debugging, it may be helpful to enable verbose logging by setting the
@@ -29,8 +33,16 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (!parser.IsValid()) {
     return 0;
   }
+
+  base::Time time;
+  std::unique_ptr<const net::RecordParsed> record_parsed;
+  do {
+    record_parsed = net::RecordParsed::CreateFrom(&parser, time);
+  } while (record_parsed);
+
   net::DnsResourceRecord record;
   while (parser.ReadRecord(&record)) {
   }
+
   return 0;
 }