AccountMobileExtension.cls

public with sharing class AccountMobileExtension {

	private final ApexPages.StandardController sCon;

	public AccountMobileExtension(ApexPages.StandardController stdController) {
		this.sCon = stdController;
	}

	public PageReference doSave() {
		PageReference pr = this.sCon.save(); 
		if (pr != null) {
			pr = new PageReference('completed://');
		}
		return pr;
	}
}