Scrollbars show the track on how much a content has been reviewed. This is an standard on every single device out there.
To enable the Material scrollbar styles, just add the md-scrollbar class to the scrollable component that you want. If you want this effect in the whole page, you can put the class in the html tag.
html tag and on Vue Material components, like md-content or md-drawer. Due to CSS limitations, the style will be applied only on Webkit/Blink browsers (Chrome, Safari and Opera).