1. Web Store: It appears to be used to install extensions from the Chrome Web Store, although it is not necessary for most of the time when using the browser.
   
2. Chromium PDF Viewer: View PDF files directly in the browser, which is sometimes quite useful.
   
3. Google Hangouts: Almost never used.
   

(Yesterday, 09:41 AM)tanquang Wrote: When checking in chrome://system/#extensions, I see that the browser comes with 3 built-in extensions:

1. Web Store: It appears to be used to install extensions from the Chrome Web Store, although it is not necessary for most of the time when using the browser.
   
2. Chromium PDF Viewer: View PDF files directly in the browser, which is sometimes quite useful.
   
3. Google Hangouts: Almost never used.
   

It can be seen that only 2 extensions are used, Web Store (rarely) and Chromium PDF Viewer (sometimes), while Google Hangouts is almost never used, even when using Google Hangouts on https://hangouts.google.com, this extension is not necessary.

Some other browsers like Supermium (removed), Thorium (will remove in next update) this extension. So I hope CentBrowser will also remove Google Hangouts, because it is useless and has no need to exist.

As for the other two extensions, Web Store and Chromium PDF Viewer, while Chromium PDF Viewer is occasionally useful, while Web Store is rarely used, it is not necessary to have it built-in, always enabled, and start up with the browser. These extensions can be installed as regular extensions, allowing users to disable/remove them if they are not used.