Thanks for the feedback ?
There is no way to simulate or execute a click over a chrome extension icon (it's a security restriction), but an automatic scroll is something that can be supported as a voice command.
What to do you think of this sequence:
1. The person says "Auto scroll"
2. The web page is scrolled down (one or two lines per second)
3. The scrolling stops soon as the person says "stop", or the scrolling got to the bottom of the page.