Examine source code of Custom Speed for Udemy

{
  "manifest_version": 2,
  "name": "CustomSpeed for Udemy",
  "version": "1.0.3",
  "description": "Learn even smarter on Udemy by setting the pace that fits your time.",
  "permissions": [
    "storage",
    "tabs",
    "*://*.udemy.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.udemy.com/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "commands": {
    "increase-speed": {
      "suggested_key": {
        "default": "Alt+Up"
      },
      "description": "Increase video speed"
    },
    "decrease-speed": {
      "suggested_key": {
        "default": "Alt+Down"
      },
      "description": "Decrease video speed"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "customspeed@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "48": "icons/icon.svg",
    "128": "icons/icon.svg"
  }
}