A few days ago, I was facing a problem "Sharepoint anonymous site prompting for credentials on a mobile phone." To resolve this issue I have done the change in "compat.browser" file in the App_Browsers folder. Changes are done as below.
<!-- Android -->
<gateway id="Android" parentID="Default">
<identification>
<userAgent match="Android" />
</identification>
<capabilities>
<capability name="isMobileDevice" value="true" />
<capability name="Platform" value="Android" />
</capabilities>
And change it to:
<capability name="isMobileDevice" value="false" />