Associate "chrome-extension://" to Chrome browser?
It's not possible, as the problem is not within Terminal, but rather in Chrome.app's URL scheme. Chrome does not outwardly expose the chrome:// and chrome-extension:// URL schemes, handling them internally (when you access chrome://history, chrome://settings, etc.). 

For example, open chrome:// does not work in Terminal:


  The file /Users/user/chrome: does not exist.


Yet, typing open twitter:// in Terminal causes the Mac Twitter app to open on my machine.



However, you can use a bash alias to achieve a similar effect, with an even easier shortcut:

alias chrome_ssh="chrome-extension://pnhechapfaindjhompbnflcldabbghjo/html/nassh.html /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome"


Add the above to your ~/.bash_profile.