Examine source code of KeepPlaying

{
  "manifest_version": 2,
  "name": "KeepPlaying",
  "description": "Prevents videos and ads from pausing when you switch tabs. Works on YouTube, Google Ads, and all websites.",
  "version": "3.1.0",
  "icons": {
    "16": "16.png",
    "48": "48.png",
    "128": "128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{24133e29-5f55-40ad-b6ea-a8cf4ae17f85}"
    }
  }
}