It looks like people will be able to see your code. If they can see your code, they can potentially use it.
- Windows:
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions - Linux and Mac:
~/Library/Application Support/Google/Chrome/Default/Extensions/or~/.config/google-chrome/Default/Extensions/
The source code is available for inspection/debugging/experimenting & whatever people might want to do. You may try to use a JavaScript obfuscator.