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

webrtc/modules/rtp_rtcp/source/rtp_utility.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/modules/rtp_rtcp/source/rtp_utility.h"
 
 #include <string.h>
 
 #include "webrtc/base/logging.h"
 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
 
 namespace webrtc {
 
 RtpData* NullObjectRtpData() {
   static NullRtpData null_rtp_data;
   return &null_rtp_data;
 }
 
 RtpFeedback* NullObjectRtpFeedback() {
   static NullRtpFeedback null_rtp_feedback;
   return &null_rtp_feedback;
 }
 
-RtpAudioFeedback* NullObjectRtpAudioFeedback() {
-  static NullRtpAudioFeedback null_rtp_audio_feedback;
-  return &null_rtp_audio_feedback;
-}
-
 ReceiveStatistics* NullObjectReceiveStatistics() {
   static NullReceiveStatistics null_receive_statistics;
   return &null_receive_statistics;
 }
 
 namespace RtpUtility {
 
 enum {
   kRtcpExpectedVersion = 2,
   kRtcpMinHeaderLength = 4,
@@ skipping 387 matching lines @@
     if (*ptr != 0) {
       return num_zero_bytes;
     }
     ptr++;
     num_zero_bytes++;
   }
   return num_zero_bytes;
 }
 }  // namespace RtpUtility
 }  // namespace webrtc