title: How change icon for MasterDetail on Android?
body: <p>I have Xamarin Forms. I need change standard icon for <code>MasterDetailPage</code>. Property Icon do not working on Android. I tried add custom renderer, but it don't work.</p>
  <pre><code>[assembly: ExportRenderer(typeof(MainPage), typeof(IconNavigationPageRenderer))]
  namespace masterDe.Droid
  {
      public class IconNavigationPageRenderer : MasterDetailPageRenderer
      {
          public IconNavigationPageRenderer(Context context):base(context) { }
          private static Android.Support.V7.Widget.Toolbar GetToolbar() =&gt; (CrossCurrentActivity.Current?.Activity as MainActivity)?.FindViewById&lt;Android.Support.V7.Widget.Toolbar&gt;(Resource.Id.toolbar);
  
  
          protected override void OnLayout(bool changed, int l, int t, int r, int b)
          {
              base.OnLayout(changed, l, t, r, b);
              var toolbar = GetToolbar();
              if (toolbar != null)
              {
                  for (var i = 0; i &lt; toolbar.ChildCount; i++)
                  {
                      var imageButton = toolbar.GetChildAt(i) as Android.Widget.ImageButton;
  
                      var drawerArrow = imageButton?.Drawable as DrawerArrowDrawable;
                      if (drawerArrow == null)
                          continue;
  
                      // replace default hamburg icon
                      imageButton.SetImageDrawable(Forms.Context.GetDrawable(Resource.Drawable.icon));
                  }
              }
          }
      }
  }
  </code></pre>
  <p><code>GetToolbar()</code> always is null. How Can I fix it?</p>