Replace is_omemo_enabled with an init var

omemo/__init__.py

@@ -214,7 +214,9 @@ class OmemoPlugin(GajimPlugin):
         jid = chat_control.contact.jid
         if account not in self.ui_list:
             self.ui_list[account] = {}
-        self.ui_list[account][jid] = Ui(self, chat_control)
+        state = self.get_omemo_state(account)
+        omemo_enabled = jid in state.omemo_enabled
+        self.ui_list[account][jid] = Ui(self, chat_control, omemo_enabled)
 
     def are_keys_missing(self, contact):
         """ Used by the ui to set the state of the PreKeyButton. """
@@ -420,12 +422,6 @@ class OmemoPlugin(GajimPlugin):
         except:
             return True
 
-    @log_calls('OmemoPlugin')
-    def is_omemo_enabled(self, contact):
-        account = contact.account.name
-        state = self.get_omemo_state(account)
-        return contact.jid in state.omemo_enabled
-
     @log_calls('OmemoPlugin')
     def omemo_enable_for(self, contact):
         """ Used by the ui to enable omemo for a specified contact """

omemo/ui.py

@@ -92,7 +92,7 @@ class Ui(object):
 
     last_msg_plain = True
 
-    def __init__(self, plugin, chat_control):
+    def __init__(self, plugin, chat_control, enabled):
         contact = chat_control.contact
         self.prekey_button = PreKeyButton(plugin, contact)
         self.checkbox = Checkbox(plugin, chat_control)
@@ -101,7 +101,7 @@ class Ui(object):
         available = plugin.has_omemo(contact)
         self.toggle_omemo(available)
 
-        self.checkbox.set_active(plugin.is_omemo_enabled(contact))
+        self.checkbox.set_active(enabled)
         self.chat_control = chat_control
 
         _add_widget(self.prekey_button, chat_control)