Examine source code of WordPress Login Autofill

{
  "manifest_version": 2,
  "name": "WordPress Login Autofill",
  "version": "1.0",
  "description": "Automatically fill in the WordPress login form",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon.png",
      "48": "icon.png",
      "128": "icon.png"
    }
  },
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "jake@efront.com.au",
      "strict_min_version": "42.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*wp-login*"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}