Early initialize recording on the ADM from WebRtcVoiceMediaChannel.

BUG=webrtc:4690

Review URL: https://codereview.webrtc.org/1827263002

Cr-Commit-Position: refs/heads/master@{#12369}
diff --git a/webrtc/media/engine/webrtcvoiceengine.h b/webrtc/media/engine/webrtcvoiceengine.h
index 0bc0933..0c2d8ba 100644
--- a/webrtc/media/engine/webrtcvoiceengine.h
+++ b/webrtc/media/engine/webrtcvoiceengine.h
@@ -235,6 +235,7 @@
     return send_codec_spec_.codec_inst.pltype != -1;
   }
   bool ValidateRtpParameters(const webrtc::RtpParameters& parameters);
+  void SetupRecording();
 
   rtc::ThreadChecker worker_thread_checker_;