This Chrome extension adds a button that, when clicked, toggles the minimum font size between two values that can be determined in the options.
It might seem unnecessary, but I wrote this for a use case I encountered myself. I frequently alternate between using an external monitor with my HiDPI Thinkpad at home and using the laptop on the go. My eyesight is quite bad, so some of the fonts in Chrome ended up being too small on the laptop's HiDPI monitor (despite increasing the font DPI in XFCE when not using the external monitor). Being able to easily increase and decrease the minimum font size solves the problem perfectly.