Examine source code of Reader Mode Activation

{
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "91.1.0",
      "id": "{b7a87310-517a-4ead-a616-c3a3440d95ba}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "browser_style": true,
    "default_title": "__MSG_extensionName__",
    "default_icon": {
      "64": "icons/logo_64.png"
    }
  },
  "description": "__MSG_extensionDescription__",
  "manifest_version": 2,
  "name": "Read Mode",
  "permissions": [
    "tabs",
    "notifications"
  ],
  "version": "1.0",
  "icons": {
    "32": "icons/logo_32.png",
    "48": "icons/logo_48.png",
    "64": "icons/logo_64.png"
  }
}