Atualize seu manifest.json para a versão mais recente!

Segue um exemplo do Manifest.json da versão 3:

{
  "manifest_version": 3,
  "name": "My Extension",
  "description": "A brief description of my extension",
  "version": "1.0.0",
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "My Extension",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "https://*.example.com/*",
    "storage"
  ],
  "background": {
    "service_worker": "background.js",
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": ["https://*.example.com/*"],
      "js": ["content.js"]
    }
  ],
  "options_page": "options.html",
  "content_security_policy": "script-src 'self' https://example.com; object-src 'self'",
  "web_accessible_resources": [
    "style.css",
    "script.js"
  ],
  "default_locale": "en",
  "incognito": "spanning",
  "minimum_chrome_version": "58",
  "oauth2": {
    "client_id": "YOUR_OAUTH2_CLIENT_ID",
    "scopes": ["https://www.googleapis.com/auth/userinfo.email"]
  }
}


  

No próximo artigo você poderá conferir o que cada atríbuto do Manifest.json significa. Bons estudos!