Fix UT failure by temporarily uncommenting

webrtc/audio/audio_send_stream.cc

 /*
  *  Copyright (c) 2015 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 257 matching lines @@
     // TODO(elad.alon): This function call could potentially reset the window,
     // setting both PLR and RPLR to unknown. Consider (during upcoming
     // refactoring) passing an indication of such an event.
     packet_loss_tracker_.OnPacketAdded(seq_num, rtc::TimeMillis());
   }
 }
 
 void AudioSendStream::OnPacketFeedbackVector(
     const std::vector<PacketFeedback>& packet_feedback_vector) {
   // TODO(elad.alon): This fails in UT; fix and uncomment.
+  // See: https://bugs.chromium.org/p/webrtc/issues/detail?id=7405
   // RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   rtc::Optional<float> plr;
   rtc::Optional<float> rplr;
   {
     rtc::CritScope lock(&packet_loss_tracker_cs_);
     packet_loss_tracker_.OnPacketFeedbackVector(packet_feedback_vector);
     plr = packet_loss_tracker_.GetPacketLossRate();
     rplr = packet_loss_tracker_.GetRecoverablePacketLossRate();
   }
   // TODO(elad.alon): If R/PLR go back to unknown, no indication is given that
@@ skipping 133 matching lines @@
         LOG(LS_WARNING) << "SetVADStatus() failed.";
         return false;
       }
     }
   }
   return true;
 }
 
 }  // namespace internal
 }  // namespace webrtc