Extensions are not supported, see: https://developers.google.com/chrome/mobile/docs/faq .
Does Chrome for Android now support the embedded WebView for a hybrid native/web app?
A Chrome-based WebView is included in Android 4.4 (KitKat) and later. See the WebView overview for details.
Does Chrome for Android support apps and extensions?
Chrome apps and extensions are currently not supported on Chrome for Android. We have no plans to announce at this time.
Can I write and deploy web apps on Chrome for Android?
Though Chrome apps are not currently supported, we would love to see great interactive web sites accessible by URL.