Simplify interface for media/cast: CastTransportSenderImpl

media/cast/test/loopback_transport.h

Index: media/cast/test/loopback_transport.h
diff --git a/media/cast/test/loopback_transport.h b/media/cast/test/loopback_transport.h
index e61ae4d7f1496f8c697099371c33a444e840857c..7f32c6fd705d34e62a44e11ef8e5e7b192a90bb1 100644
--- a/media/cast/test/loopback_transport.h
+++ b/media/cast/test/loopback_transport.h
@@ -36,6 +36,11 @@ class LoopBackTransport : public PacketSender {
 
   int64_t GetBytesSent() final;
 
+  void StartReceiving(
+      const PacketReceiverCallbackWithStatus& packet_receiver) final {}
+
+  void StopReceiving() final {}
+
   // Initiailize this loopback transport.
   // Establish a flow of packets from |pipe| to |packet_receiver|.
   //