You’ll need to restart Chrome for the extension to work correctly. When complete, you should see a multidirectional crosshair appear in your extensions bar, which is to the right of your address bar. To install AutoScroll, navigate to the extension page and click the Add to Chrome button. We’ve found that no other Chrome extension is as good as AutoScroll when it comes to mimicking the auto-scrolling functionality of Windows’ middle-click. If you’re using Chrome, it’s much easier to use an extension built specifically for the browser to achieve this.
Google Chrome: Use the AutoScroll Extension