Revert of Implemented the GetSources() in native code.

webrtc/media/engine/webrtcvoiceengine.cc

Index: webrtc/media/engine/webrtcvoiceengine.cc
diff --git a/webrtc/media/engine/webrtcvoiceengine.cc b/webrtc/media/engine/webrtcvoiceengine.cc
index a0d3cec9135cada17f88ec00ea9ce875a396c124..8fcda89962ee768153b9d6337a862309b7e67aab 100644
--- a/webrtc/media/engine/webrtcvoiceengine.cc
+++ b/webrtc/media/engine/webrtcvoiceengine.cc
@@ -1579,12 +1579,6 @@
       stream_->Stop();
     }
     playout_ = playout;
-  }
-
-  std::vector<webrtc::RtpSource> GetSources() {
-    RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
-    RTC_DCHECK(stream_);
-    return stream_->GetSources();
   }
 
  private:
@@ -2606,15 +2600,6 @@
   it->second->SetRawAudioSink(std::move(sink));
 }
 
-std::vector<webrtc::RtpSource> WebRtcVoiceMediaChannel::GetSources(
-    uint32_t ssrc) const {
-  auto it = recv_streams_.find(ssrc);
-  RTC_DCHECK(it != recv_streams_.end())
-      << "Attempting to get contributing sources for SSRC:" << ssrc
-      << " which doesn't exist.";
-  return it->second->GetSources();
-}
-
 int WebRtcVoiceMediaChannel::GetReceiveChannelId(uint32_t ssrc) const {
   RTC_DCHECK(worker_thread_checker_.CalledOnValidThread());
   const auto it = recv_streams_.find(ssrc);