Examine source code of otoran inline player

{
  "manifest_version": 2,
  "name": "otoran inline player",
  "description": "otoran内で動画を再生できるようにします。別途 https://greasyfork.org/ja/scripts/435038-embed-nicovideo-jp-1080p-support をインストールするとページ内からいいねもできるようになります。",
  "version": "1.1.0",
  "permissions": [
    "https://otoran.vercel.app/*",
    "https://embed.nicovideo.jp/watch/*",
    "https://nvapi.nicovideo.jp/v1/users/me/likes/items?*",
    "history",
    "webRequest",
    "webRequestBlocking"
  ],
  "content_scripts": [
    {
      "js": [
        "otoran.content.js"
      ],
      "matches": [
        "https://otoran.vercel.app/*"
      ]
    },
    {
      "js": [
        "nicoembed.content.js"
      ],
      "matches": [
        "https://embed.nicovideo.jp/watch/*"
      ],
      "all_frames": true
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  }
}