Examine source code of GitHub Minesweeper

{
  "manifest_version": 2,
  "name": "GitHub Minesweeper",
  "version": "1.0.1",
  "homepage_url": "https://github.com/bgonp/github-mines-extension#readme",
  "description": "Minesweeper game on GitHub profile page using calendar contributions chart",
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://github.com/*"
      ],
      "js": [
        "index.js"
      ],
      "css": [
        "index.css"
      ]
    }
  ]
}