Examine source code of BS.TO Background changer

{
  "manifest_version": 2,
  "name": "BS.TO Background changer",
  "version": "1.0.0",
  "description": "Mit der Extension kannst du das Hintergrundbild von bs.to so verändern, wie du es magst.",
  "content_scripts": [
    {
      "js": [
        "changeImage.js"
      ],
      "matches": [
        "https://bs.to/*",
        "https://burningseries.co/*"
      ],
      "run_at": "document_start"
    }
  ],
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "storage"
  ]
}