How do I go back from web in mobile.

Good Afternoon

I've been working on an app that when you select a button from facebook, take you to the page. This works wonders on the Web, because it opens a new page or have the back button in the browser. But when I take a test on an Android device, I can not get when you open the page, they can return to the app, can not I just do that with the physical button on the device back to the application.

Thank you all.

Greetings from Mexico

Edit:

I put my .capx if anyone want to see it.

Thanks again: https://www.dropbox.com/s/0s9pjhmhkoqu2 ... 20Web.capx