Prepare the AudioSendStream to be hooked up to send-side BWE.

webrtc/config.h

Index: webrtc/config.h
diff --git a/webrtc/config.h b/webrtc/config.h
index 114303e6169a55510adfa1d1884a260aef99f092..45a2ece416b113b66a8fecea84ef0e31ae9a1193 100644
--- a/webrtc/config.h
+++ b/webrtc/config.h
@@ -138,6 +138,12 @@ struct NetEqFastAccelerate {
   bool enabled;
 };
 
+struct VoicePacing {
+  VoicePacing() : enabled(false) {}
+  explicit VoicePacing(bool value) : enabled(value) {}
+  bool enabled;
+};
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_CONFIG_H_