GeoCodingAPI_Xamarin.cs

void FnGeoCodeApi()
{
        string strGeoCode = string.Format ("address={0}","Silicon Valley,CA,USA");
	string strGeoCodeFullURL = string.Format (Constants.strGeoCodingUrl,strGeoCode);
	string strResult=await FnHttpRequest(strGeoCodeFullURL); 
	if ( strResult != Constants.strException )
	{ 
		var objGeoCodeClass= JsonConvert.DeserializeObject<GoogleGeoCodeClass> (strResult);  
		if ( objGeoCodeClass.status == "OK" )
		{
			var Position = new LatLng ( objGeoCodeClass.results [0].geometry.location.lat , objGeoCodeClass.results [0].geometry.location.lng );
			string address = objGeoCodeClass.results [0].formatted_address;
		}
	} 
}
WebClient webclient;
async Task<string> FnHttpRequest(string strUri)
{ 
	webclient = new WebClient ();
	string strResultData;
	        try
		{
			strResultData= await webclient.DownloadStringTaskAsync (new Uri(strUri));
			Console.WriteLine(strResultData);
		}
		catch
		{
			strResultData = Constants.strException;
		}
		finally
		{
			if ( webclient!=null )
			{
		        	webclient.Dispose ();
		        	webclient = null; 
			}
		}
        return strResultData;
}