Examine source code of YouTube Save Current Time

{
  "manifest_version": 2,
  "name": "YouTube Save Current Time",
  "description": "A lightweight browser extension to save the current time spent in any YouTube video, for those who don't trust in the video player.",
  "author": "Micael Levi L. C.",
  "version": "1.0.0",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {},
  "icons": {
    "96": "icons/timer-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://youtube.com/*",
        "https://youtube.com/*",
        "https://www.youtube.com/*",
        "http://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}