Add rooms that the user has left under archived in v2 sync.

synapse/storage/roommember.py

@@ -124,6 +124,19 @@ class RoomMemberStore(SQLBaseStore):
             invites.event_id for invite in invites
         ]))
 
+    def get_leave_events_for_user(self, user_id):
+        """ Get all the leave events for a user
+        Args:
+            user_id (str): The user ID.
+        Returns:
+            A deferred list of event objects.
+        """
+        return self.get_rooms_for_user_where_membership_is(
+            user_id, [Membership.LEAVE]
+        ).addCallback(lambda leaves: self._get_events([
+            leave.event_id for leave in leaves
+        ]))
+
     def get_rooms_for_user_where_membership_is(self, user_id, membership_list):
         """ Get all the rooms for this user where the membership for this user
         matches one in the membership list.