Examine source code of White Mode Buttons

{
  "manifest_version": 2,
  "name": "White Mode Buttons",
  "version": "1.0",
  "description": "Idiotensicher: WhiteMode, Lesemodus, Kontrast-Boost mit Botschaften.",
  "permissions": [
    "activeTab",
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon.png"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "white-mode-buttons@example.com"
    }
  }
}