They will also warn you a few browser restarts later that the extension may be malicious and disable it for you. I know this, because I used to make my own extensions, distribute them as .crx files, and people would use them. Now they keep getting disabled. The only way around it is to list them on the chrome store. You can have an unlisted entry on the chrome store which is free, but they will remain in control of your private keys and update process. And of course they will know that the extension exists and who uses it.

The only way around this, apparently, is to install the developer edition of Chrome, which means being plagued with bugs and possible security risks. Splendid.

https://support.google.com/chrome/answer/2811969