Fix TSAN race in webrtc::voe::Channel

webrtc/voice_engine/channel.cc

Index: webrtc/voice_engine/channel.cc
diff --git a/webrtc/voice_engine/channel.cc b/webrtc/voice_engine/channel.cc
index 5f29fe401efbcc8c46e96d0c9174f78dd1dc3075..2bc07dcccb91666bc852c5e5c31b55b7863c1712 100644
--- a/webrtc/voice_engine/channel.cc
+++ b/webrtc/voice_engine/channel.cc
@@ -2742,23 +2742,26 @@ void Channel::SetRtcpRttStats(RtcpRttStats* rtcp_rtt_stats) {
   rtcp_rtt_stats_proxy_->SetRtcpRttStats(rtcp_rtt_stats);
 }
 
-void Channel::UpdateOverheadForEncoder() {
+void Channel::UpdateOverheadForEncoder(size_t overhead_per_packet) {
   audio_coding_->ModifyEncoder([&](std::unique_ptr<AudioEncoder>* encoder) {
     if (*encoder) {
-      (*encoder)->OnReceivedOverhead(transport_overhead_per_packet_ +
-                                     rtp_overhead_per_packet_);
+      (*encoder)->OnReceivedOverhead(overhead_per_packet);
     }
   });
 }
 
 void Channel::SetTransportOverhead(size_t transport_overhead_per_packet) {
+  rtc::CritScope cs(&overhead_per_packet_lock_);
   transport_overhead_per_packet_ = transport_overhead_per_packet;
-  UpdateOverheadForEncoder();
+  UpdateOverheadForEncoder(transport_overhead_per_packet_ +
+                           rtp_overhead_per_packet_);
 }
 
 void Channel::OnOverheadChanged(size_t overhead_bytes_per_packet) {

[the sun, 2017/02/28 11:13:10]

Please add:
// TODO(solenberg): Make AudioSendStream an OverheadObserver instead.

[hbos, 2017/02/28 11:44:55]

Done.

+  rtc::CritScope cs(&overhead_per_packet_lock_);
   rtp_overhead_per_packet_ = overhead_bytes_per_packet;
-  UpdateOverheadForEncoder();
+  UpdateOverheadForEncoder(transport_overhead_per_packet_ +
+                           rtp_overhead_per_packet_);
 }
 
 int Channel::GetNetworkStatistics(NetworkStatistics& stats) {