Clean away use of RtpAudioFeedback interface from RTP/RTCP receiver code.

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 5950dc75545fc713ed7e16df14b4d150bb80db2a..42c0cd44f9669f43073223fcf594af4c976b1f6d 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.cc
@@ -34,33 +34,39 @@ RtpReceiver* RtpReceiver::CreateVideoReceiver(
   if (!incoming_messages_callback)
     incoming_messages_callback = NullObjectRtpFeedback();
   return new RtpReceiverImpl(
-      clock, NullObjectRtpAudioFeedback(), incoming_messages_callback,
-      rtp_payload_registry,
+      clock, incoming_messages_callback, rtp_payload_registry,
       RTPReceiverStrategy::CreateVideoStrategy(incoming_payload_callback));
 }
 
 RtpReceiver* RtpReceiver::CreateAudioReceiver(
     Clock* clock,
-    RtpAudioFeedback* incoming_audio_feedback,
     RtpData* incoming_payload_callback,
     RtpFeedback* incoming_messages_callback,
     RTPPayloadRegistry* rtp_payload_registry) {
-  if (!incoming_audio_feedback)
-    incoming_audio_feedback = NullObjectRtpAudioFeedback();
   if (!incoming_payload_callback)
     incoming_payload_callback = NullObjectRtpData();
   if (!incoming_messages_callback)
     incoming_messages_callback = NullObjectRtpFeedback();
   return new RtpReceiverImpl(
-      clock, incoming_audio_feedback, incoming_messages_callback,
-      rtp_payload_registry,
-      RTPReceiverStrategy::CreateAudioStrategy(incoming_payload_callback,
-                                               incoming_audio_feedback));
+      clock, incoming_messages_callback, rtp_payload_registry,
+      RTPReceiverStrategy::CreateAudioStrategy(incoming_payload_callback));
+}
+
+// TODO(solenberg): Remove, after updating downstream code.
+RtpReceiver* RtpReceiver::CreateAudioReceiver(
+    Clock* clock,
+    RtpAudioFeedback* incoming_audio_feedback,
+    RtpData* incoming_payload_callback,
+    RtpFeedback* incoming_messages_callback,
+    RTPPayloadRegistry* rtp_payload_registry) {
+  return CreateAudioReceiver(clock,
+                             incoming_payload_callback,
+                             incoming_messages_callback,
+                             rtp_payload_registry);
 }
 
 RtpReceiverImpl::RtpReceiverImpl(
     Clock* clock,
-    RtpAudioFeedback* incoming_audio_messages_callback,
     RtpFeedback* incoming_messages_callback,
     RTPPayloadRegistry* rtp_payload_registry,
     RTPReceiverStrategy* rtp_media_receiver)
@@ -79,7 +85,6 @@ RtpReceiverImpl::RtpReceiverImpl(
       last_received_frame_time_ms_(-1),
       last_received_sequence_number_(0),
       nack_method_(kNackOff) {
-  assert(incoming_audio_messages_callback);
   assert(incoming_messages_callback);
 
   memset(current_remote_csrc_, 0, sizeof(current_remote_csrc_));