Examine source code of Timely

{
  "description": "Convert timestamps to not timestamps and other useful things.",
  "manifest_version": 2,
  "name": "Timely",
  "version": "1.5.2",
  "homepage_url": "https://github.com/dshuffma-ibm/timely",
  "icons": {
    "48": "icons/timely-48.png"
  },
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options/index.html"
  },
  "browser_action": {
    "default_icon": "icons/timely-32.png",
    "theme_icons": [
      {
        "light": "icons/timely-32.png",
        "dark": "icons/timely-32.png",
        "size": 32
      }
    ],
    "default_title": "Timely",
    "default_popup": "popup/timely.html"
  },
  "web_accessible_resources": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3fc845ac-3c5b-4ccc-8863-fb63d74273c2}"
    }
  }
}