cast: cleanup rtp header and parsing

media/cast/BUILD.gn

Index: media/cast/BUILD.gn
diff --git a/media/cast/BUILD.gn b/media/cast/BUILD.gn
index 188cfca8b6dc175dd02f77ac3f9225b52c5a9005..6b87e13952f388dd003408ba7c663dcbe4442e00 100644
--- a/media/cast/BUILD.gn
+++ b/media/cast/BUILD.gn
@@ -87,12 +87,12 @@ source_set("net") {
     "net/rtp/packet_storage.h",
     "net/rtp/receiver_stats.cc",
     "net/rtp/receiver_stats.h",
+    "net/rtp/rtp_defines.cc",
+    "net/rtp/rtp_defines.h",
     "net/rtp/rtp_packetizer.cc",
     "net/rtp/rtp_packetizer.h",
     "net/rtp/rtp_parser.cc",
     "net/rtp/rtp_parser.h",
-    "net/rtp/rtp_receiver_defines.cc",
-    "net/rtp/rtp_receiver_defines.h",
     "net/rtp/rtp_sender.cc",
     "net/rtp/rtp_sender.h",
     "net/udp_transport.cc",
@@ -310,12 +310,9 @@ test("cast_unittests") {
     "net/rtp/mock_rtp_payload_feedback.h",
     "net/rtp/packet_storage_unittest.cc",
     "net/rtp/receiver_stats_unittest.cc",
-    "net/rtp/rtp_header_parser.cc",
-    "net/rtp/rtp_header_parser.h",
     "net/rtp/rtp_packet_builder.cc",
     "net/rtp/rtp_packetizer_unittest.cc",
     "net/rtp/rtp_parser_unittest.cc",
-    "net/rtp/rtp_receiver_defines.h",
     "net/udp_transport_unittest.cc",
     "receiver/audio_decoder_unittest.cc",
     "receiver/frame_receiver_unittest.cc",