[Cast] Cleanup: Remove TransportXXXXXSender, an unnecessary layer of indirection.

media/cast/transport/cast_transport_config.h

Index: media/cast/transport/cast_transport_config.h
diff --git a/media/cast/transport/cast_transport_config.h b/media/cast/transport/cast_transport_config.h
index 683587080bbb3951069c262d74cb70ef8789ba44..96b771acb998a8ac3cb486d07bb8d65fbcaca3a3 100644
--- a/media/cast/transport/cast_transport_config.h
+++ b/media/cast/transport/cast_transport_config.h
@@ -108,6 +108,10 @@ struct EncodedFrame {
     return reinterpret_cast<uint8*>(string_as_array(&data));
   }
 
+  // Copies all data members except |data| to |dest|.
+  // Does not modify |dest->data|.
+  void CopyMetadataTo(EncodedFrame* dest) const;
+
   // This frame's dependency relationship with respect to other frames.
   Dependency dependency;