Examine source code of PasscodePro

{
  "manifest_version": 2,
  "name": "PasscodePro",
  "description": "Securely manage passwords for different websites without a database or vault",
  "version": "3.4resigned1",
  "permissions": [
    "contextMenus",
    "tabs",
    "https://passcod.es/*",
    "webRequest"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "vendor/browser-polyfill.js",
        "page_content/domain_suffix_list.js",
        "page_content/page_content.js"
      ],
      "all_frames": true
    }
  ],
  "background": {
    "scripts": [
      "vendor/browser-polyfill.js",
      "background_process/background_process.js"
    ]
  },
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{74af1772-6fca-4cc7-9586-3e664ad7f0ac}"
    }
  }
}