Handle padded audio packets correctly

webrtc/modules/audio_coding/acm2/acm_receiver.cc

Index: webrtc/modules/audio_coding/acm2/acm_receiver.cc
diff --git a/webrtc/modules/audio_coding/acm2/acm_receiver.cc b/webrtc/modules/audio_coding/acm2/acm_receiver.cc
index f6f1786f5e7dd234897fbd88d977bcf58e209fee..2eacefdb9d7440a8f890a71a2fd8d44a4728d704 100644
--- a/webrtc/modules/audio_coding/acm2/acm_receiver.cc
+++ b/webrtc/modules/audio_coding/acm2/acm_receiver.cc
@@ -77,6 +77,11 @@ int AcmReceiver::InsertPacket(const WebRtcRTPHeader& rtp_header,
   uint32_t receive_timestamp = 0;
   const RTPHeader* header = &rtp_header.header;  // Just a shorthand.
 
+  if (incoming_payload.empty()) {
+    neteq_->InsertEmptyPacket(rtp_header.header);
+    return 0;
+  }
+
   {
     rtc::CritScope lock(&crit_sect_);