Examine source code of Reddit Mail Checker

{
  "manifest_version": 2,
  "name": "Reddit Mail Checker",
  "version": "2.1resigned1",
  "description": "Check your Reddit orangereds anytime with simple add-on.",
  "applications": {
    "gecko": {
      "id": "jid1-GeP0lNGxbU74Cg@jetpack"
    }
  },
  "permissions": [
    "*://www.reddit.com/*",
    "alarms",
    "tabs"
  ],
  "background": {
    "scripts": [
      "build/kotlin-js-min/main/kotlin.js",
      "build/kotlin-js-min/main/reddit.mail.checker.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/loggedout-16.png",
      "32": "icons/loggedout-32.png",
      "64": "icons/loggedout-64.png"
    },
    "default_title": "Reddit mail checker (loading)"
  }
}