Examine source code of Text Toolkit : (AIO Text Tools)

{
  "manifest_version": 2,
  "name": "Text Toolkit : (AIO Text Tools)",
  "description": "All-In-One free and useful text tools collection.",
  "version": "1.1.0",
  "icons": {
    "128": "icon_128.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  }
}