Examine source code of PassLok for Email

{
  "name": "PassLok for Email",
  "short_name": "PassLok",
  "description": "High security encryption for email. PassLok is in no way associated with Gmail, Yahoo, or Outlook.",
  "version": "1.0",
  "manifest_version": 3,
  "icons": {
    "16": "img/passlok-icon16inv.png",
    "48": "img/passlok-icon48inv.png",
    "128": "img/passlok-touch-icon128.png"
  },
  "content_security_policy": {
    "extension_pages": "default-src 'self'; img-src 'self' data:; connect-src 'self' data:; style-src 'self'"
  },
  "permissions": [
    "storage",
    "alarms"
  ],
  "host_permissions": [
    "https://mail.google.com/*",
    "http://mail.google.com/*",
    "https://google.com/*",
    "http://google.com/*",
    "http://*.mail.yahoo.com/*",
    "https://*.mail.yahoo.com/*",
    "http://*.live.com/*",
    "https://*.live.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://mail.google.com/*",
        "http://mail.google.com/*",
        "http://*.mail.yahoo.com/*",
        "https://*.mail.yahoo.com/*",
        "http://*.live.com/*",
        "https://*.live.com/*"
      ],
      "css": [
        "css/content.css"
      ],
      "js": [
        "js-src/content.js"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "4email@passlok.com"
    }
  }
}