Revert of Remove unnecessary interface TelephoneEventHandler

webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc b/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc
index babad1c06999d259cc1cc98dcb56099a5e9fb8ec..190449b3ddfe6bdde9561cc16a0ce6d1387ed767 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc
@@ -200,6 +200,10 @@
   return true;
 }
 
+TelephoneEventHandler* RtpReceiverImpl::GetTelephoneEventHandler() {
+  return rtp_media_receiver_->GetTelephoneEventHandler();
+}
+
 bool RtpReceiverImpl::Timestamp(uint32_t* timestamp) const {
   rtc::CritScope lock(&critical_section_rtp_receiver_);
   if (!HaveReceivedFrame())