Examine source code of EmbedUpdater

{
  "manifest_version": 2,
  "name": "EmbedUpdater",
  "description": "Updates video embeds to make use of HTML5 video playback",
  "version": "1.3.0",
  "homepage_url": "https://github.com/M-Reimer/embedupdater",
  "author": "Manuel Reimer",
  "applications": {
    "gecko": {
      "id": "{eb8240fc-eee9-4cc7-ab15-12ac64614064}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content/framescript.js"
      ]
    }
  ]
}