Implement PlayoutDelay extension as a trait

webrtc/test/fuzzers/rtp_packet_fuzzer.cc

Index: webrtc/test/fuzzers/rtp_packet_fuzzer.cc
diff --git a/webrtc/test/fuzzers/rtp_packet_fuzzer.cc b/webrtc/test/fuzzers/rtp_packet_fuzzer.cc
index 2a67a8bea73115fc97a97867394e4d906906d490..613f125e33da0a25e3a4af9e2ae69b1280ac7aea 100644
--- a/webrtc/test/fuzzers/rtp_packet_fuzzer.cc
+++ b/webrtc/test/fuzzers/rtp_packet_fuzzer.cc
@@ -82,7 +82,8 @@ void FuzzOneInput(const uint8_t* data, size_t size) {
         packet.GetExtension<TransportSequenceNumber>(&seqnum);
         break;
       case kRtpExtensionPlayoutDelay:
-        // TODO(katrielc) Add this once it's written.
+        PlayoutDelay playout;
+        packet.GetExtension<PlayoutDelayLimits>(&playout);
         break;
     }
   }