Unseen for Facebook Messenger

manifest.json

{
  "author": "SMART TEAM",
  "background": {
    "page": "background.html",
    "persistent": true
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/icon48.png"
    },
    "default_popup": "/popup.html"
  },
  "content_scripts": [
    {
      "css": [
        "css/read_button.css"
      ],
      "js": [
        "js/lib/jquery.js",
        "js/lib/relaxed-json.min.js",
        "js/read_button.js"
      ],
      "matches": [
        "*://*.facebook.com/*"
      ],
      "run_at": "document_end"
    }
  ],
  "content_security_policy": "script-src 'self' 'unsafe-eval' https://www.google-analytics.com; object-src 'self'",
  "description": "Unseen for FB Messenger stop the 'seen' feature from Messenger. Your friends won´t see 'seen' when you read their messages.",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "manifest_version": 2,
  "name": "Unseen for Facebook Messenger",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "tabs",
    "https://*.facebook.com/*",
    "http://*.facebook.com/*",
    "storage",
    "cookies"
  ],
  "version": "4.0.0",
  "web_accessible_resources": [
    "*"
  ],
  "-ms-preload": {
    "backgroundScript": "backgroundScriptsAPIBridge.js",
    "contentScript": "contentScriptsAPIBridge.js"
  },
  "update_url": "https://edge.microsoft.com/extensionwebstorebase/v1/crx"
}