Well there were two mistake i was doing. One was very obvious the other was not.
String AD_UNIT_ID = "pub-4445095092775025";
actually this is a publisher id and not ad unit id.
2. layout.addView(adView, adParams); layout.addView(gameView);
This will actually keep my game view over the adview thus adview will never be shown. the proper way of adding adview would be.
layout.addView(gameView);
layout.addView(adView, adParams);