Examine source code of Slido

{
  "name": "Slido",
  "icons": {
    "16": "icons/16x16.png",
    "48": "icons/48x48.png",
    "128": "icons/128x128.png"
  },
  "browser_action": {
    "default_icon": "icons/128x128.png",
    "default_popup": "popup.html"
  },
  "description": "Engage your audience with live polling and Q&A without ever leaving Google Slides",
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true,
    "open_in_tab": false
  },
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "https://docs.google.com/presentation/*"
      ],
      "js": [
        "js/environment.js",
        "js/commons.js",
        "js/content-google-slides.js"
      ],
      "match_about_blank": true
    }
  ],
  "permissions": [
    "storage",
    "tabs",
    "https://docs.google.com/presentation/*",
    "https://*.sli.do/*",
    "https://*.slido.com/*",
    "https://script.google.com/*"
  ],
  "externally_connectable": {
    "matches": [
      "*://*.sli.do/*",
      "*://*.slido.com/*",
      "*://*.googleusercontent.com/*"
    ]
  },
  "incognito": "split",
  "web_accessible_resources": [
    "oauth-callback.html",
    "icons/16x16.png",
    "icons/48x48.png",
    "icons/128x128.png",
    "js/environment.js",
    "js/commons.js",
    "js/content-google-slides.js"
  ],
  "version": "64.63.7",
  "browser_specific_settings": {
    "gecko": {
      "id": "{cea81df6-229d-4427-801a-4961166bd9d2}"
    }
  }
}