title: Fix google map marker in center
body: <p>In my flutter app. I am using <code>google_maps_plugin</code> . The link is <a href="https://github.com/flutter/plugins/tree/master/packages/google_maps_flutter" rel="noreferrer">https://github.com/flutter/plugins/tree/master/packages/google_maps_flutter</a> .
  I want to fix the marker in center of map without movable after draging the map. 
  I want it likes <a href="http://jsfiddle.net/UuDA6/" rel="noreferrer">http://jsfiddle.net/UuDA6/</a>
  In my code i am using <code>MarkerOption</code> for placing the marker. </p>
  
  <pre><code>    MarkerOptions options = new MarkerOptions(   
          alpha: 1.0,
          anchor: Offset(0.5, 1.0),
          consumeTapEvents: false,
          draggable: false,
          flat: false,
          icon: BitmapDescriptor.defaultMarker,
          infoWindowAnchor: Offset(0.5, 0.0),
          infoWindowText: InfoWindowText.noText,
          position: LatLng(17.411439, 78.5486697),
          rotation: 0.0,
          visible: true,
          zIndex: 0.0,
      );
  </code></pre>
  
  <p>But in the <code>position</code> i want to know how to give the center of map.</p>
  
  <p>If any one have idea about it please share it.</p>