I have an extension in the Chrome Web Store and I like knowing roughly how many people are using it via the "N users" and ratings on its page.
However, I don't really like loading the whole "product" page just to see a couple of numbers and thought I'd try to make a little widget that would display it instead. However, I can't find any API documentation for the Chrome Web Store.
I would a call like /webstore/api/v1/appid.json
to exist, but the closest things I've found in searching only concern the Licensing API.
Is there an official Chrome Web Store API for user metrics?
This is no such API.
You can use Google Analytics inside an extension to track users manually.
If you don't need anything fancy, just a number of installs and users, there is My Extensions extension, it will track those numbers for you.