Examine source code of TL;DR

{
  "manifest_version": 2,
  "name": "TL;DR",
  "version": "1.5",
  "description": "Adds ability to create TL;DR text out of the text page with https://tldr.cloud",
  "icons": {
    "48": "icons/tldr-48.png",
    "96": "icons/tldr-96.png"
  },
  "browser_action": {
    "default_title": "TL;DR",
    "default_popup": "show_tldr.html",
    "default_icon": {
      "48": "icons/tldr-48.png",
      "96": "icons/tldr-96.png"
    }
  },
  "permissions": [
    "https://us-central1-tldr-278619.cloudfunctions.net/extract-summary",
    "tabs"
  ]
}