Examine source code of Let's agile

{
  "manifest_version": 2,
  "name": "Let's agile",
  "description": "Let's agile tools shortcut",
  "version": "0.0.11",
  "author": "Heptartle",
  "icons": {
    "16": "tab-icon.png",
    "32": "tab-icon.png",
    "128": "tab-icon.png"
  },
  "browser_action": {
    "default_icon": "tab-icon.png",
    "default_popup": "popup.html",
    "default_title": "Let's agile"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c49b6928-5ca7-452a-8685-c2b6971a8d3f}"
    }
  }
}