Examine source code of CO₂ flight comparison

{
  "name": "__MSG_appName__",
  "version": "0.1",
  "description": "__MSG_appDesc__",
  "manifest_version": 2,
  "default_locale": "en",
  "content_scripts": [
    {
      "matches": [
        "https://www.google.com/flights*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "storage",
    "https://co2offset.atmosfair.de/api/*",
    "https://api.atmosfair.de/api/*"
  ]
}