Examine source code of Crunchyroll Sync Toolv

{
  "manifest_version": 2,
  "name": "Crunchyroll Sync Tool",
  "version": "1.0",
  "description": "Synchronize two Crunchyroll videos for mixed dubbing and subtitles.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8ac3ffaf-e8f1-4fca-a1db-861e9e2f8e79}"
    }
  }
}