Examine source code of Link Tree

{
  "name": "Link Tree",
  "version": "1.2",
  "description": "Displays the link URL of the web page in a tree format.",
  "icons": {
    "16": "icons/icon-16.png",
    "19": "icons/icon-19.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/icon-16.png",
    "default_title": "Link Tree"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{8fe94f17-89ca-48e8-8ddd-043a1bf3b599}"
    }
  }
}