[As currently defined](https://github.com/mozilla-b2g/gaia/pull/10351/files#L1R135), `setFrameSrc` must specify one argument:

```javascript
var setFrameSrc = function(thumbnail) {
  el.width = thumbnail.width || MIN_THUMBNAIL_WIDTH_HEIGHT;
  el.height = thumbnail.height || MIN_THUMBNAIL_WIDTH_HEIGHT;
```

If we want to support invoking without arguments, we'll need something like `thumbnail = thumbnail || {}` (be sure to update the function's description if you decide to do this). Alternatively, you could bind an empty object: `setTimeout(setFrameSrc.bind(null, {}))`