I think this block would be clearer if you did something like this:

```
// Don't update the seekbar when the user is seeking or the audio is not
// playing.
if (this.isSeeking || !this.isPlaying)
  return;

// If ModeManager is undefined, then the music app was launched by the open
// activity; otherwise, only seek the audio when the mode is PLAYER because
// updating the UI will slow down the ot her pages, such as the scrolling in
// ListView.
if (typeof ModeManager === 'undefined' ||
    ModeManager.currentMode === MODE_PLAYER) {
  this.seekAudio();
}
```