Examine source code of SyncClick

{
  "manifest_version": 2,
  "name": "SyncClick",
  "version": "1.0.2",
  "description": "Sync video playback and clicks across multiple users",
  "icons": {
    "16": "icon-192.png",
    "48": "icon-192.png",
    "96": "icon-192.png",
    "128": "icon-192.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "syncclick@vnoisy",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "activeTab",
    "storage",
    "webNavigation",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "browser-polyfill.min.js",
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.min.js",
        "signalr.min.js",
        "content.js"
      ],
      "run_at": "document_end",
      "all_frames": true
    }
  ],
  "browser_action": {
    "default_icon": {
      "16": "icon-192.png",
      "32": "icon-192.png",
      "48": "icon-192.png"
    },
    "default_title": "SyncClick - Click to Open"
  },
  "web_accessible_resources": [
    "icon-192.png",
    "icon-512.png",
    "favicon.ico"
  ]
}