[Cast] Remove AudioDecoder's dependency on WebRTC, and refactor/clean-up AudioReceiver.

media/cast/rtp_receiver/rtp_parser/rtp_parser.cc

Index: media/cast/rtp_receiver/rtp_parser/rtp_parser.cc
diff --git a/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc b/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc
index fabc5fd93638ad53ca242a6a52d0939097483dd5..9a06c2b7d2962de80d1369e6d7674485f669fca1 100644
--- a/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc
+++ b/media/cast/rtp_receiver/rtp_parser/rtp_parser.cc
@@ -112,7 +112,7 @@ bool RtpParser::ParseCast(const uint8* packet,
   if (rtp_header->max_packet_id < rtp_header->packet_id)
     return false;
 
-  data_callback_->OnReceivedPayloadData(data_ptr, data_length, rtp_header);
+  data_callback_->OnReceivedPayloadData(data_ptr, data_length, *rtp_header);
   return true;
 }