Examine source code of CheggSkip

{
  "manifest_version": 2,
  "name": "CheggSkip",
  "version": "1.0.1",
  "description": "Allow skip or Exit a question on chegg",
  "icons": {
    "48": "border-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "cheggextension@github.com"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.chegg.com/*"
      ],
      "js": [
        "skip.js"
      ]
    }
  ]
}