Examine source code of Password Instead Asterisk

{
  "manifest_version": 2,
  "name": "Password Instead Asterisk",
  "version": "1.0",
  "description": "Show hidden password fields temporarily",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "64": "icon64.png",
      "128": "icon128.png"
    }
  },
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ca698b58-2530-4e12-bd56-ebbfeaf109e5}",
      "strict_min_version": "112.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}