Examine source code of Sudoku v2

{
  "manifest_version": 2,
  "name": "Sudoku v2",
  "version": "1.0.1",
  "description": "Play the well-designed Sudoku anytime offline!",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "storage",
    "unlimitedStorage"
  ],
  "browser_action": {
    "default_icon": {
      "16": "static/images/16.png",
      "32": "static/images/32.png",
      "48": "static/images/48.png",
      "64": "static/images/64.png",
      "128": "static/images/128.png"
    }
  },
  "icons": {
    "16": "static/images/16.png",
    "32": "static/images/32.png",
    "48": "static/images/48.png",
    "64": "static/images/64.png",
    "128": "static/images/128.png"
  },
  "minimum_chrome_version": "70",
  "offline_enabled": true,
  "browser_specific_settings": {
    "gecko": {
      "id": "{ee0df715-4484-488e-aa64-2ad706cef21f}"
    }
  }
}