Examine source code of CF FetchCodes

{
  "manifest_version": 2,
  "name": "CF FetchCodes",
  "version": "25.12.7",
  "description": "Fetch Accepted Codes of CodeForces Friends",
  "icons": {
    "16": "assets/icon16.png",
    "20": "assets/icon20.png",
    "32": "assets/icon32.png",
    "48": "assets/icon48.png",
    "64": "assets/icon64.png",
    "96": "assets/icon_96_96.png",
    "128": "assets/icon_128_128.png"
  },
  "permissions": [
    "activeTab",
    "https://codeforces.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://codeforces.com/contest/*/problem/*",
        "https://codeforces.com/problemset/problem/*"
      ],
      "js": [
        "js/ContentFriends.js",
        "js/popup.js",
        "js/run_prettify.js"
      ],
      "css": [
        "css/ContentFriends.css",
        "css/popup.css"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "assets/icon_128_128.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{791b3d1a-35d1-457f-aec5-388a93ac4129}"
    }
  }
}