Did you know that you can examine the source code of almost every Chrome browser extension? No, either did I until a few days ago when I was researching the subject.
You don't even need to install the extension in order to examine it.
Here's how to do it. First, go to the Chrome web store and find the extension you want to examine. Assuming you're using Chrome, right-click the extension and choose Copy Link Address. Then go to the Chrome Extension Downloader page at https://chrome-extension-downloader.com/ and paste in the address you just copied. In no time at all you'll have the CRX file on your computer.
Once the file is downloaded, rename it from CRX to ZIP and you can examine its contents. Note, however, that the Windows built-in zip file extractor won't work with these files. Use 7Zip or WinZip or WinRar instead.