Examine source code of LinkInfo

{
  "manifest_version": 2,
  "name": "LinkInfo",
  "version": "1.0",
  "description": "Shows information about a link, mainly whether it's going to be opened in a new tab.",
  "icons": {
    "48": "assets/open_link_in_new_tab.svg"
  },
  "web_accessible_resources": [
    "assets/open_link_in_new_tab.svg"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d165b611-5bb6-4553-8ba2-f5477c9dfad4}"
    }
  }
}