Fix media_image_urls for universal media player (#4765)

* Fix media_image_urls for universal media player

* Linter fixes

homeassistant/components/media_player/universal.py

@@ -263,6 +263,17 @@ class UniversalMediaPlayer(MediaPlayerDevice):
         """Image url of current playing media."""
         return self._child_attr(ATTR_ENTITY_PICTURE)
 
+    @property
+    def entity_picture(self):
+        """
+        Return image of the media playing.
+
+        The universal media player doesn't use the parent class logic, since
+        the url is coming from child entity pictures which have already been
+        sent through the API proxy.
+        """
+        return self.media_image_url
+
     @property
     def media_title(self):
         """Title of current playing media."""

tests/components/media_player/test_universal.py

@@ -28,6 +28,7 @@ class MockMediaPlayer(media_player.MediaPlayerDevice):
         self._supported_media_commands = 0
         self._source = None
         self._tracks = 12
+        self._media_image_url = None
 
         self.service_calls = {
             'turn_on': mock_service(
@@ -92,6 +93,11 @@ class MockMediaPlayer(media_player.MediaPlayerDevice):
         """Supported media commands flag."""
         return self._supported_media_commands
 
+    @property
+    def media_image_url(self):
+        """Image url of current playing media."""
+        return self._media_image_url
+
     def turn_on(self):
         """Mock turn_on function."""
         self._state = STATE_UNKNOWN
@@ -400,6 +406,26 @@ class TestMediaPlayer(unittest.TestCase):
         ump.update()
         self.assertEqual(1, ump.volume_level)
 
+    def test_media_image_url(self):
+        """Test media_image_url property."""
+        TEST_URL = "test_url"
+        config = self.config_children_only
+        universal.validate_config(config)
+
+        ump = universal.UniversalMediaPlayer(self.hass, **config)
+        ump.entity_id = media_player.ENTITY_ID_FORMAT.format(config['name'])
+        ump.update()
+
+        self.assertEqual(None, ump.media_image_url)
+
+        self.mock_mp_1._state = STATE_PLAYING
+        self.mock_mp_1._media_image_url = TEST_URL
+        self.mock_mp_1.update_ha_state()
+        ump.update()
+        # mock_mp_1 will convert the url to the api proxy url. This test
+        # ensures ump passes through the same url without an additional proxy.
+        self.assertEqual(self.mock_mp_1.entity_picture, ump.entity_picture)
+
     def test_is_volume_muted_children_only(self):
         """Test is volume muted property w/ children only."""
         config = self.config_children_only