Examine source code of ff2mpv

{
  "description": "Tries to play links in MPV",
  "manifest_version": 3,
  "name": "ff2mpv",
  "version": "6.0.0",
  "icons": {
    "16": "icons/icon_16x16.png",
    "32": "icons/icon_32x32.png",
    "48": "icons/icon_48x48.png",
    "64": "icons/icon_64x64.png",
    "256": "icons/icon_256x256.png"
  },
  "action": {
    "default_icon": "icons/icon_48x48.png",
    "default_title": "Play the current URL in MPV"
  },
  "commands": {
    "_execute_action": {
      "description": "Play the current URL in mpv"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "ff2mpv@yossarian.net"
    }
  },
  "background": {
    "scripts": [
      "ff2mpv.js"
    ],
    "service_worker": "ff2mpv.js"
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": false
  },
  "permissions": [
    "nativeMessaging",
    "contextMenus",
    "activeTab",
    "storage",
    "scripting"
  ]
}