Examine source code of Start Select Plus

{
  "manifest_version": 2,
  "name": "Start Select Plus",
  "description": "Torne o Start Select um lugar mais agradável",
  "version": "1.2resigned1",
  "permissions": [
    "storage",
    "tabs",
    "http://www.startselect.com.br/*"
  ],
  "applications": {
    "gecko": {
      "id": "start@select.com"
    }
  },
  "browser_action": {
    "default_title": "SS Plus",
    "default_popup": "options.html"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://www.startselect.com.br/*"
      ],
      "js": [
        "jquery-3.3.1.min.js",
        "main.js",
        "js/spectrum.js"
      ]
    }
  ],
  "options_page": "options.html"
}