Examine source code of HTML Video FPS Counter.

{
  "manifest_version": 2,
  "name": "HTML Video FPS Counter.",
  "version": "1.2resigned1",
  "description": "View the fps of a running video ",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/fps.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{78fca45b-3a22-4425-b7e1-315c60a92037}"
    }
  }
}