Examine source code of Feature the Flag

{
  "manifest_version": 2,
  "name": "Feature the Flag",
  "version": "0.1.3",
  "description": "Toggle feature flags from the extension bar",
  "options_ui": {
    "page": "config/index.html"
  },
  "browser_action": {
    "default_popup": "popup/index.html"
  },
  "icons": {
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'"
}