On windows the location of chrome's extensions is "AppData\Local\Google\Chrome\User Data\Default\Extensions". You can read the source code of all of your installed extensions there. This requires you to install the extension first. It is also possible to download the crx file of any extension from the chrome web store and just unzip it to inspect the source, though i'm not sure how to do it with the official chrome. Ungoogled chromium downloads the crx file if you press "add to chrome" and then cancel.
I diff'd the chrome extension against the github repo and they are basically the same, outside of a few lines in the README.md missing and the manifest.json containing an update URL key to "https://clients2.google.com/service/update2/crx".