Examine source code of YouTube Repeat Button

{
  "name": "YouTube™ Repeat Button",
  "description": "Adds a repeat button to the HTML5 player to loop over a single track after 1 second delay",
  "version": "0.3.0",
  "manifest_version": 3,
  "permissions": [
    "storage",
    "scripting"
  ],
  "host_permissions": [
    "*://www.youtube.com/*"
  ],
  "background": {
    "service_worker": "worker.js",
    "scripts": [
      "worker.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "data/inject.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "homepage_url": "https://webextension.org/listing/youtube-tools.html?from=repeat-button",
  "icons": {
    "16": "data/icons/16.png",
    "32": "data/icons/32.png",
    "48": "data/icons/48.png",
    "64": "data/icons/64.png",
    "128": "data/icons/128.png",
    "256": "data/icons/256.png",
    "512": "data/icons/512.png"
  },
  "commands": {
    "toggle_repeat": {
      "description": "Toggle Loop for current tab"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{28c18e92-ab27-403f-973d-49d1d0fa7665}",
      "strict_min_version": "148.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}