Examine source code of DistanceCalculator

{
  "manifest_version": 2,
  "name": "Distance2City",
  "version": "1.2",
  "description": "Checks the distance between a city and a default location.",
  "permissions": [
    "contextMenus",
    "clipboardWrite",
    "storage",
    "browserSettings"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icon48.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "icon48.png"
    }
  },
  "applications": {
    "gecko": {
      "id": "city-distance-checker@yourdomain.com",
      "strict_min_version": "60.0"
    }
  },
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ]
    }
  ],
  "options_ui": {
    "page": "settings.html",
    "browser_style": true
  }
}