Examine source code of GitHub Custom Notifier

{
  "manifest_version": 3,
  "name": "GitHub Custom Notifier",
  "description": "Customize which GitHub Event to be notified.",
  "version": "0.0.5",
  "short_name": "GitHub Custom Notifier",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "64": "icon/64.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "homepage_url": "https://github.com/qiweiii/github-custom-notifier",
  "permissions": [
    "alarms",
    "storage",
    "offscreen"
  ],
  "optional_permissions": [
    "notifications"
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "bell.ogg"
      ],
      "matches": [
        "*://*/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5a5c41da-afc4-4154-adcd-335fe5250b9d}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "GitHub Custom Notifier",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}