Examine source code of TwoTab

{
  "manifest_version": 2,
  "name": "twotab",
  "version": "1.0.2",
  "license": "MIT",
  "browser_specific_settings": {
    "gecko": {
      "id": "twotab@happens.lol"
    }
  },
  "start_url": ".",
  "display": "standalone",
  "theme_color": "#82aaff",
  "background_color": "#212121",
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  }
}