Examine source code of Crono

{
  "name": "Crono",
  "description": "__MSG_appDesc__",
  "short_name": "Crono",
  "version": "3.7.0",
  "manifest_version": 2,
  "default_locale": "en",
  "homepage_url": "https://crono.app",
  "icons": {
    "48": "icons/48x48.png",
    "64": "icons/64x64.png",
    "128": "icons/128x128.png",
    "256": "icons/256x256.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/48x48.png",
      "64": "icons/64x64.png",
      "128": "icons/128x128.png",
      "256": "icons/256x256.png"
    }
  },
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": true
  },
  "permissions": [
    "tabs",
    "clipboardRead",
    "contextMenus",
    "notifications",
    "activeTab",
    "storage",
    "downloads"
  ],
  "content_security_policy": "object-src 'self'; script-src 'self' https://storage.googleapis.com; img-src * 'self' data:;"
}