Examine source code of Reddit Checker

{
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "reddit-checker@afnankhan",
      "strict_min_version": "61.0"
    }
  },
  "name": "Reddit Checker",
  "version": "2018.9.21resigned1",
  "description": "Check if the current url has been submitted to reddit.",
  "icons": {
    "128": "images/icon.png"
  },
  "browser_action": {
    "default_title": "Reddit Checker",
    "default_icon": "images/icon.png",
    "default_popup": "html/popup.html",
    "browser_style": false
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "permissions": [
    "tabs",
    "storage",
    "https://www.reddit.com/*"
  ]
}