Simplify {,Set}UlpfecConfig interface.

webrtc/modules/rtp_rtcp/include/rtp_rtcp.h

Index: webrtc/modules/rtp_rtcp/include/rtp_rtcp.h
diff --git a/webrtc/modules/rtp_rtcp/include/rtp_rtcp.h b/webrtc/modules/rtp_rtcp/include/rtp_rtcp.h
index cbf953db0fd97a4bc8fecd7831d323ccbfa65b04..25041b8ff91a4b8051710ce2ed4917b634656ad6 100644
--- a/webrtc/modules/rtp_rtcp/include/rtp_rtcp.h
+++ b/webrtc/modules/rtp_rtcp/include/rtp_rtcp.h
@@ -453,9 +453,9 @@ class RtpRtcp : public Module {
   // Video
   // **************************************************************************
 
-  // Turn on/off ULPFEC.
-  virtual void SetUlpfecConfig(bool enabled,
-                               int red_payload_type,
+  // Set RED and ULPFEC payload types. A payload type of -1

[danilchap, 2016/10/27 11:53:40]

which of the two payload types should be -1 to turn ulpfec off?

[brandtr, 2016/10/28 07:46:31]

ulpfec_payload_type == -1 means that ULPFEC is off and red_payload_type == -1
means that RED is off. I have expanded the comment to clarify this.

In a consistent system, these should always be enabled/disabled together.
However, due to a workaround involving RTX (see
https://codereview.webrtc.org/1649493004), for now we will always send RED if it
has been negotiated in the SDP, regardless if we are using ULPFEC or not. I will
most likely remove this workaround, but for now we need the ability to turn
these off individually.

+  // means that the functionality is turned off.
+  virtual void SetUlpfecConfig(int red_payload_type,
                                int ulpfec_payload_type) = 0;
 
   virtual int32_t SetFecParameters(const FecProtectionParams* delta_params,