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 87379abd8dfc3f7b03dee9edd62275b52875e3d7..27472c9136ccb1d02fbfa3f10397ccce3d5deb97 100644
--- a/webrtc/api/webrtcsession.h
+++ b/webrtc/api/webrtcsession.h
@@ -232,7 +232,7 @@ 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;