Examine source code of Link Extractor Plus

{
  "manifest_version": 2,
  "name": "Link Extractor",
  "version": "1.0",
  "description": "Extract all links from the current webpage",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "downloads"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{be6b881f-41fb-4f84-b1c2-bc17304e9027}"
    }
  }
}