private void notifyBubble(boolean open) {
        if (open) {
            onShowBubble();
        } else {
            onHideBubble();
        }
    }
If {@code enabled} is false the indicator won't appear. By default popup indicator is
enabled.
app/src/main/java/com/duan/musicoco/view/discreteseekbar/DiscreteSeekBar.java