Examine source code of Planio Custom Script

{
  "manifest_version": 2,
  "name": "Planio Custom Script",
  "description": "This extension add styles to planio agile board",
  "version": "1.8",
  "browser_action": {
    "default_title": "icon.png"
  },
  "content_scripts": [
    {
      "js": [
        "jquery.min.js",
        "jquery.cookie.js",
        "inject.js"
      ],
      "matches": [
        "*://frs.plan.io/*/agile/*"
      ]
    }
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "permissions": [
    "*://frs.plan.io/*/agile/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{6e3bf788-a51f-4845-b175-10361e081a7a}"
    }
  }
}