Note to Self: On just expire timer update, set TIMER_UPDATE flag

js/models/conversations.js

@@ -1258,6 +1258,8 @@
       let promise;
 
       if (this.isMe()) {
+        const flags =
+          textsecure.protobuf.DataMessage.Flags.EXPIRATION_TIMER_UPDATE;
         const dataMessage = await textsecure.messaging.getMessageProto(
           this.get('id'),
           null,
@@ -1266,7 +1268,8 @@
           [],
           message.get('sent_at'),
           expireTimer,
-          profileKey
+          profileKey,
+          flags
         );
         return message.sendSyncMessageOnly(dataMessage);
       }

libtextsecure/sendmessage.js

@@ -772,7 +772,8 @@ MessageSender.prototype = {
     preview,
     timestamp,
     expireTimer,
-    profileKey
+    profileKey,
+    flags
   ) {
     const attributes = {
       recipients: [number],
@@ -783,6 +784,7 @@ MessageSender.prototype = {
       preview,
       expireTimer,
       profileKey,
+      flags,
     };
 
     const message = new Message(attributes);