Revert of Added kNotAProbe definiton to PacketInfo.

webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h

Index: webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
diff --git a/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h b/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
index 73571b8dc244557ed8a6676f9a3f7bb1973bf794..364d9718372f5aeb4641abc268f54e40a36f65da 100644
--- a/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
+++ b/webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h
@@ -278,8 +278,6 @@
         payload_size(payload_size),
         probe_cluster_id(probe_cluster_id) {}
 
-  static constexpr int kNotAProbe = -1;
-
   // Time corresponding to when this object was created.
   int64_t creation_time_ms;
   // Time corresponding to when the packet was received. Timestamped with the