Examine source code of Gmail POP3 Auto Refresh

{
  "name": "Gmail POP3 Auto Refresh",
  "description": "Refresh unlimited POP3 email accounts of Gmail with a frequency of one minute for free.",
  "version": "1.4",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.min.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Gmail POP3 Auto Refresh",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "contact@evanjuge.fr"
    }
  },
  "content_scripts": [
    {
      "js": [
        "contentscript.min.js"
      ],
      "matches": [
        "*://mail.google.com/*"
      ]
    }
  ],
  "web_accessible_resources": [
    "script.min.js"
  ]
}