title: How to add Google basemaps in openlayers-3?
body: <p>In openlayers-2, we can add google basemaps(satellite,physical,hybrid,etc.). I need to add google basemaps in openlayer-3. How can I add google basemaps???</p>
  
  <p>CODE in openlayers-3</p>
  
  <pre><code>map = new ol.Map({
        layers: [
           new ol.layer.Group({
              layers: [
                 new ol.layer.Tile({
                    source: null,
                    visible:false
                    }),
                    new ol.layer.Tile({
                    source: new ol.source.MapQuest({layer: 'sat'})
                    }),
                    new ol.layer.Tile({
                    source: new ol.source.OSM(),
                    visible:false
                      })
                   ]})
                  ],
                  target: 'map',
                  view: new ol.View({
                      center:[28.566667, 4.01666699999998],
                      zoom:7
                      }),
                  controls: ol.control.defaults({
  
                         attribution:false
  
                  }).extend([
                      scaleLineControl
                  ]),
              });
  
          lyr=new ol.layer.Tile({  source: new ol.source.TileWMS({
              url: 'http://localhost:8080/geoserver/wms',
              params: {'LAYERS': 'test:test', 'TILED': true},
              serverType: 'geoserver'
              })
          });
  map.addLayer(lyr);
  </code></pre>
  
  <p>I need to google basemaps instead of osm and mapquest.</p>