pubsub: Add a PubSubPayload trait.

src/avatar.rs

@@ -5,6 +5,7 @@
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 use crate::hashes::Sha1HexAttribute;
+use crate::pubsub::PubSubPayload;
 use crate::util::helpers::WhitespaceAwareBase64;
 
 generate_element!(
@@ -16,6 +17,8 @@ generate_element!(
     ]
 );
 
+impl PubSubPayload for Metadata {}
+
 generate_element!(
     /// Communicates avatar metadata.
     Info, "info", AVATAR_METADATA,
@@ -49,6 +52,8 @@ generate_element!(
     )
 );
 
+impl PubSubPayload for Data {}
+
 #[cfg(test)]
 mod tests {
     use super::*;