Examine source code of Grammarly Plus

{
  "manifest_version": 2,
  "name": "Grammarly Plus",
  "version": "1.0",
  "description": "Checks grammar, punctuation, and writing style as you type.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4a5fd632-26d7-4796-9e88-d79fb2665943}"
    }
  }
}