Add fuzzers for SDP and STUN parsing.

webrtc/test/fuzzers/stun_validator_fuzzer.cc

Index: webrtc/test/fuzzers/stun_validator_fuzzer.cc
diff --git a/webrtc/test/fuzzers/audio_decoder_isac_incoming_packet_fuzzer.cc b/webrtc/test/fuzzers/stun_validator_fuzzer.cc
similarity index 65%
copy from webrtc/test/fuzzers/audio_decoder_isac_incoming_packet_fuzzer.cc
copy to webrtc/test/fuzzers/stun_validator_fuzzer.cc
index 9e490d3d4ad968a5fa0e81305bdd958e79e21d18..1f919f59dc58d4aa141cf94ac0f6a35e56be6b65 100644
--- a/webrtc/test/fuzzers/audio_decoder_isac_incoming_packet_fuzzer.cc
+++ b/webrtc/test/fuzzers/stun_validator_fuzzer.cc
@@ -8,12 +8,16 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/modules/audio_coding/codecs/isac/main/include/audio_decoder_isac.h"
-#include "webrtc/test/fuzzers/audio_decoder_fuzzer.h"
+#include <stddef.h>
+#include <stdint.h>
+
+#include "webrtc/p2p/base/stun.h"
 
 namespace webrtc {
 void FuzzOneInput(const uint8_t* data, size_t size) {
-  AudioDecoderIsac dec(16000);
-  FuzzAudioDecoderIncomingPacket(data, size, &dec);
+  const char* message = reinterpret_cast<const char*>(data);
+
+  cricket::StunMessage::ValidateFingerprint(message, size);
+  cricket::StunMessage::ValidateMessageIntegrity(message, size, "");
 }
 }  // namespace webrtc