Examine source code of Domain Swap

{
  "manifest_version": 2,
  "name": "Domain Swap",
  "version": "1.1.0",
  "description": "Automatically redirect domains based on custom patterns",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "storage",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "theme_icons": [
      {
        "light": "icons/icon-16.png",
        "dark": "icons/icon-16-dark.png",
        "size": 16
      },
      {
        "light": "icons/icon-32.png",
        "dark": "icons/icon-32-dark.png",
        "size": 32
      },
      {
        "light": "icons/icon-48.png",
        "dark": "icons/icon-48-dark.png",
        "size": 48
      },
      {
        "light": "icons/icon-96.png",
        "dark": "icons/icon-96-dark.png",
        "size": 96
      }
    ],
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "domain-swap@example.com"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "icons/theme/*.png",
    "icons/actions/*.png"
  ]
}