Examine source code of NoteLift

{
  "manifest_version": 2,
  "name": "NoteLift",
  "description": "Extract highlighted text into module-wise revision notes",
  "version": "0.2",
  "browser_action": {
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "contextMenus",
    "storage",
    "downloads"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "notelift@rohitdubey",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}