Examine source code of metamask

{
  "manifest_version": 2,
  "name": "Search with YouTube or Google",
  "version": "1.0",
  "description": "Search selected text in Google or YouTube with right-click.",
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "contextMenus"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5d4cacbc-f113-4df5-932b-73e3221a9807}",
      "strict_min_version": "112.0"
    }
  }
}