In general I'd much prefer a scroll indicator to a scroll bar on mobile. Google Play Music gets this precisely wrong: the album list lets you click a play button on the album cover as a shortcut, but the button is so close to the edge of the screen that it's very difficult to avoid hitting the scroll bar area and scrolling to a random section of the list instead of hitting play. So you have to seek to the album you want again, and, because you are optimistic beyond rationality, you try again, and whoops! Did it again...