Examine source code of Open Graph Preview

{
  "manifest_version": 2,
  "name": "Open Graph Preview",
  "version": "1.0.4",
  "description": "Preview what users will see if this webpage is shared on Facebook. Uses the webpage's OG tags.",
  "icons": {
    "48": "icons/og-dark-48.png",
    "96": "icons/og-dark-96.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/og-dark-96.png",
    "theme_icons": [
      {
        "light": "icons/og-96.png",
        "dark": "icons/og-dark-96.png",
        "size": 32
      }
    ],
    "default_title": "Open Graph Preview",
    "default_popup": "popup/popup.html"
  },
  "web_accessible_resources": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{6e262423-d612-4f29-be6e-e83aa641645d}"
    }
  }
}