Added missing names in extension api jsons

chrome/common/extensions/api/mediaPlayerPrivate.json

 [
   {
     "namespace": "mediaPlayerPrivate",
     "nodoc": "true",
     "types": [
       {
         "id": "Playlist",
         "type": "object",
         "description": "Mediaplayer playlist stored in the browser (it extsts even if the mediaplayer is closed).",
         "properties": {
@@ skipping 80 matching lines @@
       {
         "name": "showPlaylistPanel",
         "description": "Shows the playlist panel.",
         "parameters": []
       }
     ],
     "events": [
       {
         "name": "onPlaylistChanged",
         "type": "function",
-        "descrition": "Notifies that playlist content or state has been changed. Data could be retrieved via 'getPlaylist'.",
+        "description": "Notifies that playlist content or state has been changed. Data could be retrieved via 'getPlaylist'.",
         "parameters": []
       }
     ]
   }
 ]