Examine source code of Zoomer

{
  "manifest_version": 2,
  "name": "Zoomer",
  "version": "1.4",
  "description": "Load web pages at 100% zoom level for better experience.",
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.hex.a2z.com/board/*"
      ],
      "js": [
        "prezoomify.js"
      ],
      "run_at": "document_start"
    },
    {
      "matches": [
        "*://*.hex.a2z.com/board/*"
      ],
      "js": [
        "postzoomify.js"
      ],
      "run_at": "document_end"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}