In 2015 Google introduced a new API for Chrome which made it possible to connect to bluetooth devices – through the browser (Link).
For a browser thats a big step. Why would you need to connect a browser to a physical thing? Well, physical web things are coming fast (There is a smart pillow that tracks your sleep!). In order to use them correctly, you always have to install a companion app. This sucks. Once these physical devices are here for the mass marked and not just a funny gadget, you will have a massive load of apps whose only purpose is to connect to a thing. Google is going to change this.
How exactly this can work is nicely explained by Scott Jenson, employee at google and one of the fathers of all this: