What are the ways to do web automation with a Chrome extension?

What I want to do is, develop an extension that adds a button to a site, and when a user clicks on that button, the extension should start doing some web automation, i.e. go to another website and complete a certain task there. However, that whole process should not be visible to the user and should happen in the background. My question is, is it possible to do this with any of Chrome’s APIs (and if so, please point me to it), or do I have to use a web automation library to do this? E.g., since I am using JavaScript, I’d import this automation library https://github.com/segmentio/nightmare into the chrome extension, and do the automation with it. I’m just thinking there should be a cleaner way than this one.

Just to clarify, the idea here is not to do something in the user’s browser without their knowing about it. It’s the main and obvious use of the extension.

Limit of the number of HTTP requests that can be sent to Facebook without being banned or getting captcha

I am building a Chrome Extension that needs to send around 10 HTTP GET requests on behalf of the user, to different web pages on Facebook. This is supposed to happen around once a week (so basically, 10 requests a week).

So my question is, is there a known limit to the number of times that I can send HTTP GET requests (using XMLHttpRequest in JavaScript) to Facebook?
Does it raise ‘red flags’ at Facebook when they receive a number of requests all at the same time, by the same user?