Examine source code of QuickLoop

{
  "manifest_version": 2,
  "name": "QuickLoop",
  "version": "1.0.0",
  "description": "Quick A-B looping for audio/video in the current tab. Mark A/B via hotkeys, save 3 favorites, overlay shows loop duration.",
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "storage",
    "activeTab",
    "tabs",
    "notifications"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon-48.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "web_accessible_resources": [
    "assets/*",
    "icons/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@quickloop-example",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}