Examine source code of Foot+

{
  "browser_specific_settings": {
    "gecko": {
      "id": "footplus@footplus.com"
    }
  },
  "background": {
    "scripts": [
      "worker.js"
    ]
  },
  "default_locale": "fr",
  "content_scripts": [
    {
      "js": [
        "scripts/site.js"
      ],
      "matches": [
        "*://foot.streamonsport.fr/*",
        "*://footstreaming24.fr/*",
        "*://fussballlivestreams.de/*"
      ],
      "run_at": "document_start",
      "all_frames": true
    },
    {
      "css": [
        "styles/footplus.css"
      ],
      "js": [
        "scripts/footplus.js"
      ],
      "matches": [
        "https://www.google.com/*",
        "https://www.google.be/*",
        "https://www.google.fr/*",
        "https://www.google.de/*",
        "https://www.google.at/*",
        "https://www.google.ch/*"
      ],
      "run_at": "document_start"
    }
  ],
  "description": "__MSG_desc__",
  "icons": {
    "48": "icons/48x48.png",
    "96": "icons/96x96.png",
    "128": "icons/128x128.png"
  },
  "manifest_version": 2,
  "name": "__MSG_name__",
  "permissions": [
    "activeTab",
    "storage",
    "*://*/"
  ],
  "version": "1.0.0.2"
}