mpris: Add default config and config schema

mopidy/frontends/mpris/__init__.py

@@ -1,10 +1,20 @@
 from __future__ import unicode_literals
 
 import mopidy
-from mopidy import ext
-from mopidy.exceptions import ExtensionError
+from mopidy import exceptions, ext
+from mopidy.utils import formatting, config
 
 
+default_config = """
+[ext.mpris]
+
+# If the MPRIS extension should be enabled or not
+enabled = true
+
+# Location of the Mopidy .desktop file
+desktop_file = /usr/share/applications/mopidy.desktop
+"""
+
 __doc__ = """
 Frontend which lets you control Mopidy through the Media Player Remote
 Interfacing Specification (`MPRIS <http://www.mpris.org/>`_) D-Bus
@@ -26,9 +36,11 @@ An example of an MPRIS client is the `Ubuntu Sound Menu
   :attr:`mopidy.settings.DESKTOP_FILE`. See :ref:`install-desktop-file` for
   details.
 
-**Settings:**
+**Default config:**
 
-- :attr:`mopidy.settings.DESKTOP_FILE`
+.. code-block:: ini
+
+%(config)s
 
 **Usage:**
 
@@ -53,7 +65,7 @@ Now you can control Mopidy through the player object. Examples:
 - To quit Mopidy through D-Bus, run::
 
     player.Quit(dbus_interface='org.mpris.MediaPlayer2')
-"""
+""" % {'config': formatting.indent(default_config)}
 
 
 class Extension(ext.Extension):
@@ -62,16 +74,18 @@ class Extension(ext.Extension):
     version = mopidy.__version__
 
     def get_default_config(self):
-        return '[ext.mpris]'
+        return default_config
 
-    def validate_config(self, config):
-        pass
+    def get_config_schema(self):
+        schema = config.ExtensionConfigSchema()
+        schema['desktop_file'] = config.String()
+        return schema
 
     def validate_environment(self):
         try:
             import dbus  # noqa
         except ImportError as e:
-            raise ExtensionError('Library dbus not found', e)
+            raise exceptions.ExtensionError('dbus library not found', e)
 
     def get_frontend_classes(self):
         from .actor import MprisFrontend