Examine source code of MAL HoverInfo

{
  "name": "MAL HoverInfo",
  "description": "Show a popup when hovering over MyAnimeList links displaying info about the anime with a button to add it to your Plan to Watch list",
  "version": "2.4resigned1",
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "malhoverinfo@osusearch.com"
    }
  },
  "background": {
    "scripts": [
      "lib/jquery-2.1.3.min.js",
      "js/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>",
        "*://*/*"
      ],
      "js": [
        "lib/jquery-2.1.3.min.js",
        "js/main.js"
      ],
      "css": [
        "css/styles.css"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "<all_urls>",
    "*://*/*",
    "storage"
  ],
  "web_accessible_resources": [
    "img/add_to_ptw.png"
  ],
  "icons": {
    "48": "img/icon_48.png",
    "128": "img/icon_128.png"
  }
}