Examine source code of Quick Definition v

{
  "manifest_version": 2,
  "name": "Quick Definition",
  "version": "1.0",
  "description": "Shows a quick definition when you highlight a word.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "quick-definition@example.com",
      "strict_min_version": "60.0"
    }
  }
}