Examine source code of Get Rate

{
  "manifest_version": 2,
  "name": "Get Rate",
  "version": "1.0",
  "icons": {
    "16": "/icons/icon16.png",
    "48": "/icons/icon48.png",
    "128": "/icons/icon16.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://codeforces.com/problemset/problem/*/*"
      ],
      "js": [
        "content.js"
      ]
    },
    {
      "matches": [
        "*://codeforces.com/contest/*/problem/*"
      ],
      "js": [
        "content2.js"
      ]
    }
  ],
  "browser_action": {
    "default_title": "LostTime",
    "default_icon": "/icons/icon128.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{4a9835e0-003a-444c-ac1a-5aed952d652f}"
    }
  }
}