Examine source code of YouTube Player Counter

{
  "manifest_version": 2,
  "name": "YT Player Counter",
  "version": "1.0",
  "description": "Licznik w prawym górnym rogu odtwarzacza YouTube, sterowany G i H oraz Z do resetu",
  "author": "Eppc",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_title": "Włącz/wyłącz licznik"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{da1cfd59-1c91-4768-8af3-1fa68ebb3f3d}"
    }
  }
}