Examine source code of Metastream

{
  "manifest_version": 2,
  "name": "Metastream",
  "version": "1.0",
  "description": "Watch videos together with friends from various platforms.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*",
        "https://vimeo.com/*",
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{14221bd0-8a0e-4c9c-83f7-cc78bf819251}"
    }
  }
}