Examine source code of LastSeen Updater

{
  "manifest_version": 2,
  "name": "LastSeen Updater",
  "author": "lastseen.me",
  "homepage_url": "https://lastseen.me",
  "short_name": "LastSeen Updater",
  "description": "Updates your LastSeen time with browser usage",
  "version": "1.0.6resigned1",
  "applications": {
    "gecko": {
      "id": "{12f8a335-f65c-47f2-a9cf-9c92fd545500}",
      "strict_min_version": "42.0"
    }
  },
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "background": {
    "page": "background.html"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "permissions": [
    "activeTab",
    "storage",
    "https://lastseen.me/*"
  ]
}