Revert of Remove audio/video distinction for probe packets.

webrtc/modules/remote_bitrate_estimator/test/packet.h

Index: webrtc/modules/remote_bitrate_estimator/test/packet.h
diff --git a/webrtc/modules/remote_bitrate_estimator/test/packet.h b/webrtc/modules/remote_bitrate_estimator/test/packet.h
index 9aa596c1bd7f32d7ea9cd753f6259dd8a364e22c..4a361c4dc20b7bce9e170cfb2e8933f426176b7c 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/packet.h
+++ b/webrtc/modules/remote_bitrate_estimator/test/packet.h
@@ -42,6 +42,8 @@
   virtual void set_sender_timestamp_us(int64_t sender_timestamp_us) {
     sender_timestamp_us_ = sender_timestamp_us;
   }
+  virtual void set_paced(bool paced) { paced_ = paced; }
+  virtual bool paced() const { return paced_; }
   virtual int64_t creation_time_ms() const {
     return (creation_time_us_ + 500) / 1000;
   }
@@ -56,6 +58,7 @@
   int64_t send_time_us_;  // Time the packet left last processor touching it.
   int64_t sender_timestamp_us_;  // Time the packet left the Sender.
   size_t payload_size_;  // Size of the (non-existent, simulated) payload.
+  bool paced_;           // True if sent through paced sender.
 };
 
 class MediaPacket : public Packet {