You don't have any devices - Google Play website

Go to Settings > Apps > All > Scroll Down And Select Google Play Store > Force stop and clear data.
Also do the same for "Google Play Services" (Just for the safe side)
Then open the play store again on your device and accept the terms and conditions.

Wait 15 minutes or 30 minutes or 1 hour, you will see your device. 

Android - Google Maps inside an App

In AndroidManifest.xml
------------------------
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />


In the Java code for the activity
---------------------------------
add "implements LocationListener" to the defination of the class


String MapUrl = "http://www.google.com/maps?q=37.423156,-122.084917";

//MapUrl = "http://maps.google.com/maps?q=Pizza,texas&ui=maps";

private WebView _webView;

_webView = (WebView)_yourrelativelayourSrc.findViewById(R.id.layout_webview);

_webView.getSettings().setJavaScriptEnabled(true);
_webView.getSettings().setBuiltInZoomControls(true);
_webView.getSettings().setSupportZoom(true);

LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
String provider = locationManager.getBestProvider(criteria,true);
//In order to make sure the device is getting the location, request updates.
locationManager.requestLocationUpdates(provider, 1, 0, this);
mostRecentLocation = locationManager.getLastKnownLocation(provider);

MapUrl = "http://www.google.com/maps?q=" + mostRecentLocation.getLatitude().toString() + "," +
 mostRecentLocation.getLongitude().toString();

final String centerURL = "javascript:centerAt(" +  mostRecentLocation.getLatitude() + "," +
  mostRecentLocation.getLongitude()+ ")";

_webView.setWebChromeClient(new WebChromeClient()
{
     public void onProgressChanged(WebView view, int progress)
     {
            // Activities and WebViews measure progress with different scales.
            // The progress meter will automatically disappear when we reach 100%
            ((Activity) activity).setProgress(progress * 1000);
     }

});

//Wait for the page to load then send the location information
_webView.setWebViewClient(new WebViewClient(){
    @Override
    public void onPageFinished(WebView view, String url){
      _webView.loadUrl(centerURL);
    }
});

_webView.loadUrl(MapUrl);