Examine source code of Link Filter

{
  "author": "Miikka Kulmala",
  "homepage_url": "https://github.com/milzer/firefox-link-filter",
  "manifest_version": 2,
  "name": "Link Filter",
  "version": "2.1",
  "description": "Filters links",
  "icons": {
    "48": "icons/link-filter.svg"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/link-filter.svg",
    "default_title": "Link Filter",
    "default_popup": "popup/link-filter.html"
  }
}