Remove chain of methods in RtpRtcp module to get current payload frequency for RTCP SRs

webrtc/modules/rtp_rtcp/source/rtp_sender.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_sender.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_sender.cc b/webrtc/modules/rtp_rtcp/source/rtp_sender.cc
index 551466690f31ad686262fe21268471480591032f..8d3bc9ec537c61d3e1f68019d320b17dee84214d 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_sender.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_sender.cc
@@ -326,10 +326,6 @@ int8_t RTPSender::SendPayloadType() const {
   return payload_type_;
 }
 
-int RTPSender::SendPayloadFrequency() const {
-  return audio_ != NULL ? audio_->AudioFrequency() : kVideoPayloadTypeFrequency;
-}
-
 void RTPSender::SetMaxPayloadLength(size_t max_payload_length) {
   // Sanity check.
   RTC_DCHECK(max_payload_length >= 100 && max_payload_length <= IP_PACKET_SIZE)