Examine source code of Slither.io Zoom Mod

{
  "manifest_version": 3,
  "name": "Slither.io Zoom Mod",
  "version": "1.1.0",
  "description": "A lightweight zoom mod for slither.io",
  "browser_specific_settings": {
    "gecko": {
      "id": "{7856d5fa-10a7-44d8-9d25-a4be5952f11c}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "declarativeNetRequestWithHostAccess"
  ],
  "host_permissions": [
    "*://slither.io/*",
    "*://slither.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "action": {
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png"
    },
    "default_title": "Slither.io Zoom Mod",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://slither.io/*",
        "*://slither.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "engine.js"
      ],
      "matches": [
        "*://slither.io/*",
        "*://slither.com/*"
      ]
    }
  ]
}