Examine source code of Gradientus

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "description": "__MSG_extensionDescription__",
  "version": "1.2.1",
  "author": "Cynthia Pereira",
  "homepage_url": "https://github.com/cynthiapereira/webextension-gradientus",
  "applications": {
    "gecko": {
      "id": "webextension-gradientus@cynthiapereira.com",
      "strict_min_version": "57.0"
    }
  },
  "icons": {
    "16": "gradientus.svg",
    "48": "gradientus.svg",
    "96": "gradientus.svg",
    "128": "gradientus.svg"
  },
  "permissions": [
    "alarms",
    "theme"
  ],
  "background": {
    "scripts": [
      "gradientus.js"
    ]
  },
  "default_locale": "en"
}