Examine source code of gen-pass

{
  "manifest_version": 2,
  "name": "Password Generator",
  "version": "1.0",
  "description": "Generate a random password",
  "icons": {
    "48": "icons/lock-48.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/lock-48.png",
    "default_title": "Password Generator",
    "default_popup": "popup/generator.html"
  }
}