Lint fixes and faster updating to universal media player.

1) Many lint fixes.
2) Bound the Universal Media Player to its dependencies so that its
state will be updated when one of its dependencies is changed.

homeassistant/components/media_player/universal.py

@@ -8,10 +8,14 @@ https://home-assistant.io/components/media_player.universal/
 """
 
 # pylint: disable=import-error
+from copy import copy
 import logging
 
+from homeassistant.helpers.event import track_state_change
+
 from homeassistant.const import (
-    STATE_IDLE, STATE_OFF, CONF_NAME, ATTR_ENTITY_ID, ATTR_ENTITY_PICTURE,
+    STATE_IDLE, STATE_ON, STATE_OFF, CONF_NAME,
+    ATTR_ENTITY_ID, ATTR_ENTITY_PICTURE,
     SERVICE_TURN_OFF, SERVICE_TURN_ON,
     SERVICE_VOLUME_UP, SERVICE_VOLUME_DOWN, SERVICE_VOLUME_SET,
     SERVICE_VOLUME_MUTE,
@@ -52,7 +56,8 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
     if not validate_config(config):
         return
 
-    player = UniversalMediaPlayer(config[CONF_NAME],
+    player = UniversalMediaPlayer(hass,
+                                  config[CONF_NAME],
                                   config[CONF_CHILDREN],
                                   config[CONF_COMMANDS],
                                   config[CONF_ATTRS])
@@ -106,8 +111,8 @@ def validate_commands(config):
         config[CONF_COMMANDS] = {}
     elif not isinstance(config[CONF_COMMANDS], dict):
         _LOGGER.warning(
-            'Universal Media Player (%s) specified commands not dict in config.'
-            ' They will be ignored.',
+            'Universal Media Player (%s) specified commands not dict in '
+            'config. They will be ignored.',
             config[CONF_NAME])
         config[CONF_COMMANDS] = {}
 
@@ -129,14 +134,17 @@ def validate_attributes(config):
 
 class UniversalMediaPlayer(MediaPlayerDevice):
     """ Represents a universal media player in HA """
+    # pylint: disable=too-many-public-methods
 
-    def __init__(self, name, children, commands, attributes):
+    def __init__(self, hass, name, children, commands, attributes):
+        # pylint: disable=too-many-arguments
+        self.hass = hass
         self._name = name
         self._children = children
         self._cmds = commands
         self._attrs = attributes
 
-        # [todo] Update when children update
+        track_state_change(hass, self.dependencies, self.update_state)
 
     def _entity_lkp(self, entity_id=None, state_attr=None, state_as_obj=True):
         """ Looks up an entity state from hass """
@@ -187,6 +195,14 @@ class UniversalMediaPlayer(MediaPlayerDevice):
         self.hass.services.call(DOMAIN, service_name, service_data,
                                 blocking=True)
 
+    @property
+    def dependencies(self):
+        """ List of entity ids of entities that the mp depends on for state """
+        depend = copy(self._children)
+        for entity in self._attrs.values():
+            depend.append(entity[0])
+        return depend
+
     @property
     def master_state(self):
         """ gets the master state from entity or none """
@@ -205,7 +221,7 @@ class UniversalMediaPlayer(MediaPlayerDevice):
     @property
     def active_child_state(self):
         """ The state of the active child or None """
-        for child_id, child_state in self.children.items():
+        for child_state in self.children.values():
             if child_state and child_state.state not in OFF_STATES:
                 return child_state
 
@@ -241,7 +257,8 @@ class UniversalMediaPlayer(MediaPlayerDevice):
     @property
     def is_volume_muted(self):
         """ boolean if volume is muted """
-        return self._override_or_child_attr(ATTR_MEDIA_VOLUME_MUTED)
+        return self._override_or_child_attr(ATTR_MEDIA_VOLUME_MUTED) \
+            in [True, STATE_ON]
 
     @property
     def media_content_id(self):
@@ -410,3 +427,7 @@ class UniversalMediaPlayer(MediaPlayerDevice):
     def media_play_pause(self):
         """ media_play_pause media player. """
         self._child_service(SERVICE_MEDIA_PLAY_PAUSE)
+
+    def update_state(self, *_):
+        """ event to trigger a state update in HA """
+        self.update_ha_state()