Revert of Delete Rtx-related methods from RTPPayloadRegistry.

webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h

Index: webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h
diff --git a/webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h b/webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h
index 7173f9f249f663298e5792ccea349c4439d68ded..eb552b84e1ef3affd22727392f0b9c83c9239d41 100644
--- a/webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h
+++ b/webrtc/modules/rtp_rtcp/include/rtp_payload_registry.h
@@ -53,7 +53,19 @@
 
   void SetRtxPayloadType(int payload_type, int associated_payload_type);
 
+  bool IsRtx(const RTPHeader& header) const;
+
+  bool RestoreOriginalPacket(uint8_t* restored_packet,
+                             const uint8_t* packet,
+                             size_t* packet_length,
+                             uint32_t original_ssrc,
+                             const RTPHeader& header);
+
   bool IsRed(const RTPHeader& header) const;
+
+  // Returns true if the media of this RTP packet is encapsulated within an
+  // extra header, such as RTX or RED.
+  bool IsEncapsulated(const RTPHeader& header) const;
 
   bool GetPayloadSpecifics(uint8_t payload_type, PayloadUnion* payload) const;