Examine source code of Cashback beruby

{
  "manifest_version": 2,
  "name": "Cashback beruby",
  "description": "Cashback beruby",
  "version": "2.7",
  "icons": {
    "16": "images/b_icon_16.png",
    "32": "images/b_icon_32.png",
    "48": "images/b_icon_48.png",
    "128": "images/b_icon_128.png"
  },
  "permissions": [
    "<all_urls>",
    "tabs",
    "browsingData"
  ],
  "browser_action": {
    "default_icon": {
      "16": "images/b_icon_16.png",
      "32": "images/b_icon_32.png",
      "48": "images/b_icon_48.png",
      "128": "images/b_icon_128.png"
    },
    "default_title": "Beruby",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "browser-polyfill.js",
      "background-script.js",
      "jquery-3.2.1.min.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.js",
        "jquery-3.2.1.min.js",
        "content-script.js"
      ],
      "css": [
        "custom.css",
        "./popup/icons.css"
      ]
    }
  ],
  "web_accessible_resources": [
    "images/logo_beruby.png",
    "templates/*",
    "fonts/Comfortaa-Light.ttf",
    "custom.css"
  ],
  "default_locale": "es",
  "browser_specific_settings": {
    "gecko": {
      "id": "{8e539cdb-a1c4-40ce-b7dc-3055b97e28c9}"
    }
  }
}