WebCenter: Mobile Page Variant Not Working

Even after creating mobile page variant for specific pages, on actual device it's not rendering the created page variant.

The solution is to change the User Agent for the Desktop Chrome to do not match anything that contains Android.
So the corrected User Agent String for the Desktop Chrome looks like this: 

.(Windows|Macintosh|Linux)((?!Android).)+Chrome.+Safari.

You can change this under Administration -> Device Settings -> Desktop Chrome -> Actions -> Edit

If you install a Firefox Add-on to override the User Agent, for example User Agent Overrider at https://addons.mozilla.org/en-us/firefox/addon/user-agent-overrider/ then you can specify the user agent for Nexus 5
(Mozilla/5.0 (Linux; Android 4.4.2; Nexus 5 Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.59 Mobile Safari/537.36)

Reference:
https://support.oracle.com/epmos/faces/DocumentDisplay?id=1614457.1