Examine source code of Page change notifier

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "notifier.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "64": "icons/notifier-48.png"
    },
    "default_title": "Page checker"
  },
  "icons": {
    "64": "icons/notifier-48.png"
  },
  "description": "Monitor speific page part and notify about it",
  "manifest_version": 2,
  "name": "Page change notifier",
  "options_ui": {
    "page": "options.html"
  },
  "permissions": [
    "storage",
    "notifications"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "page-change-notifier@nouc.dev"
    }
  },
  "web_accessible_resources": [
    "sound/ringtone.mp3"
  ],
  "version": "1.0"
}