Examine source code of TravIt

{
  "manifest_version": 2,
  "name": "TravIt - Travel Itinerary in your calendar",
  "short_name": "TravIt",
  "version": "0.1.3",
  "description": "A simple and lightweight browser extension that adds a send-to-calendar button to the online Google Maps application.",
  "content_scripts": [
    {
      "matches": [
        "*://*.google.com/maps/*",
        "*://maps.google.com/*"
      ],
      "js": [
        "content.bundle.js"
      ],
      "css": [
        "css/colors.css",
        "css/googlemaps.css"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "icons/*/*.png"
  ],
  "icons": {
    "16": "icons/ldpi/TravIt.png",
    "48": "icons/hdpi/TravIt.png",
    "128": "icons/xxxhdpi/TravIt.png"
  },
  "browser_action": {
    "browser_style": true,
    "default_popup": "popup.html"
  },
  "permissions": [
    "identity",
    "notifications",
    "storage",
    "*://www.googleapis.com/calendar/v3/users/me/calendarList",
    "webRequest"
  ],
  "background": {
    "page": "background.html"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "content_security_policy": "https://apis.google.com;",
  "browser_specific_settings": {
    "gecko": {
      "id": "travit@yesyouken.space",
      "strict_min_version": "62.0"
    }
  }
}