Ensure timer updates show in convo before initiating message

js/models/conversations.js

@@ -878,11 +878,17 @@
       });
 
       source = source || textsecure.storage.user.getNumber();
-      const timestamp = receivedAt || Date.now();
+
+      // When we add a disappearing messages notification to the conversation, we want it
+      //   to be above the message that initiated that change, hence the subtraction.
+      const timestamp = (receivedAt || Date.now()) - 1;
 
       const message = this.messageCollection.add({
+        // Even though this isn't reflected to the user, we want to place the last seen
+        //   indicator above it. We set it to 'unread' to trigger that placement.
+        unread: 1,
         conversationId: this.id,
-        type: receivedAt ? 'incoming' : 'outgoing',
+        // No type; 'incoming' messages are specially treated by conversation.markRead()
         sent_at: timestamp,
         received_at: timestamp,
         flags: textsecure.protobuf.DataMessage.Flags.EXPIRATION_TIMER_UPDATE,

js/views/message_view.js

@@ -94,6 +94,7 @@
       this.conversation = this.model.getExpirationTimerUpdateSource();
       this.listenTo(this.conversation, 'change', this.render);
       this.listenTo(this.model, 'unload', this.remove);
+      this.listenTo(this.model, 'change', this.onChange);
     },
     render_attributes() {
       const seconds = this.model.get('expirationTimerUpdate').expireTimer;
@@ -114,6 +115,13 @@
       }
       return { content: timerMessage };
     },
+    onChange() {
+      this.addId();
+    },
+    addId() {
+      // This is important to enable the lastSeenIndicator when it's just been added.
+      this.$el.attr('id', this.id());
+    },
   });
 
   Whisper.KeyChangeView = Whisper.View.extend({