Navigating to http://whatsmyuseragent.com/ shows me my stock Android browser on my Galaxy Nexus running 4.2.1 has the user agent
Mozilla/5.0 (X11; Linux x86_
I think you are searching for this:
Android native browser not updated above version 534.30 so you can filter to the version and Android UA string combination (above we can presume its a Chrome browser)
Here's my sample JavaScript code:
(If you need specific styling I would add a class to the body with the following JS snippet)
var defectAndroid = $window.navigator && $window.navigator.userAgent.indexOf('534.30') > 0 && $window.navigator.userAgent.toLowerCase().match(/android/);
if (defectAndroid) {
// sample code specific for your Android Stock browser
}
(Some Android devices reporting 'android' that's why we need the lower case conversation)