Prevent a voice channel from sending data before a renderer is set.

webrtc/api/webrtcsession.h

Index: webrtc/api/webrtcsession.h
diff --git a/webrtc/api/webrtcsession.h b/webrtc/api/webrtcsession.h
index 70265d30434e012369a508bf0e847553bb17dd07..c0d86f2871e27e7b4de73a533ed89c226477e6a3 100644
--- a/webrtc/api/webrtcsession.h
+++ b/webrtc/api/webrtcsession.h
@@ -234,7 +234,7 @@ class WebRtcSession : public AudioProviderInterface,
   void SetAudioSend(uint32_t ssrc,
                     bool enable,
                     const cricket::AudioOptions& options,
-                    cricket::AudioRenderer* renderer) override;
+                    cricket::AudioSource* source) override;
   void SetAudioPlayoutVolume(uint32_t ssrc, double volume) override;
   void SetRawAudioSink(uint32_t ssrc,
                        rtc::scoped_ptr<AudioSinkInterface> sink) override;