Differentiate between the WebView and Chrome for Android

Hi, I am sorry for the previous error. I fixed it and this is a new pull request.

I had problems with some stock android browsers that use chrome webview. That browsers doesn' t have the add to homescreen feature. I checked chrome documentation and you can differentiate chrome and chrome webviews searching the "Version" string in the user agent. You can confirm it checking the following page https://developer.chrome.com/multidevice/user-agent#webview_user_agent

I hope this helps, and thank you for sharing your project.

Regards,
Juan