Examine source code of CP Buddy

{
  "manifest_version": 2,
  "name": "cf-helper",
  "version": "3.0",
  "description": "enables extra features on codefoces.com",
  "content_scripts": [
    {
      "matches": [
        "*://*.codeforces.com/*",
        "*://*.atcoder.jp/contests/*",
        "*://*.codechef.com/*/problems/*",
        "*://*.codechef.com/problems/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ]
}