[IMP] im_livechat: add gc of empty sessions in the autovacuum cron

addons/im_livechat/data/im_livechat_channel_data.xml

@@ -1,20 +1,5 @@
 <?xml version="1.0"?>
 <odoo>
-    <data noupdate="1">
-        <!-- Remove automatically the empty anonoymous sessions -->
-        <record id="ir_cron_remove_empty_session" model="ir.cron">
-            <field name="name">[im_livechat] Remove empty anonymous sessions</field>
-            <field name="interval_number">1</field>
-            <field name="interval_type">days</field>
-            <field name="numbercall">-1</field>
-            <field name="doall" eval="False"/>
-            <field name="model">mail.channel</field>
-            <field name="function">cron_remove_empty_session</field>
-            <field name="active" eval="True"/>
-        </record>
-
-    </data>
-
     <data>
         <!-- Smiley for rating to be displayed in the conversation -->
         <record id="mail_shortcode_rating_0" model="mail.shortcode">

addons/im_livechat/models/__init__.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*
 import im_livechat_channel
+import ir_autovacuum
 import mail_channel
 import rating

addons/im_livechat/models/ir_autovacuum.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo import api, models
+
+
+class AutoVacuum(models.AbstractModel):
+    _inherit = 'ir.autovacuum'
+
+    @api.model
+    def power_on(self, *args, **kwargs):
+        self.pool['mail.channel'].remove_empty_livechat_sessions()
+        return super(AutoVacuum, self).power_on(*args, **kwargs)

addons/im_livechat/models/mail_channel.py

@@ -62,8 +62,8 @@ class MailChannel(models.Model):
         return values
 
     @api.model
-    def cron_remove_empty_session(self):
-        hours = 1 # never remove empty session created within the last hour
+    def remove_empty_livechat_sessions(self):
+        hours = 1  # never remove empty session created within the last hour
         self.env.cr.execute("""
             SELECT id as id
             FROM mail_channel C