Allow parsing empty RTCP TargetBitrate messages, but stop sending them.

webrtc/modules/rtp_rtcp/source/rtcp_receiver.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.
  */
 
@@ skipping 103 matching lines @@
       receiver_only_(receiver_only),
       rtp_rtcp_(owner),
       rtcp_bandwidth_observer_(rtcp_bandwidth_observer),
       rtcp_intra_frame_observer_(rtcp_intra_frame_observer),
       transport_feedback_observer_(transport_feedback_observer),
       bitrate_allocation_observer_(bitrate_allocation_observer),
       main_ssrc_(0),
       remote_ssrc_(0),
       xr_rrtr_status_(false),
       xr_rr_rtt_ms_(0),
+      oldest_tmmbr_info_ms_(0),
       last_received_rr_ms_(0),
       last_increased_sequence_number_ms_(0),
       stats_callback_(nullptr),
       packet_type_counter_observer_(packet_type_counter_observer),
       num_skipped_packets_(0),
       last_skipped_packets_warning_ms_(clock->TimeInMilliseconds()) {
   RTC_DCHECK(owner);
   memset(&remote_sender_info_, 0, sizeof(remote_sender_info_));
 }
 
@@ skipping 914 matching lines @@
       } else {
         candidates.push_back(it->second.tmmbr_item);
         ++it;
       }
     }
   }
   return candidates;
 }
 
 }  // namespace webrtc