Added AppBuilder and Initialize

src/Android/Avalonia.Android/AndroidPlatform.cs

@@ -1,17 +1,27 @@
+using System;
+using System.IO;
 using Avalonia.Android.CanvasRendering;
 using Avalonia.Android.Platform;
 using Avalonia.Android.Platform.Input;
-using Avalonia.Android.Platform.Specific;
+using Avalonia.Android.Platform.SkiaPlatform;
+using Avalonia.Controls;
 using Avalonia.Controls.Platform;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Platform;
 using Avalonia.Shared.PlatformSupport;
-using Avalonia.Skia;
+
-using System;
+namespace Avalonia
-using System.Collections.Generic;
+{
-using Avalonia.Android.Platform.SkiaPlatform;
+    public static class AndroidApplicationExtensions
-using System.IO;
+    {
+        public static AppBuilder UseAndroid(this AppBuilder builder)
+        {
+            builder.WindowingSubsystem = Avalonia.Android.AndroidPlatform.Initialize;
+            return builder;
+        }
+    }
+}
 
 namespace Avalonia.Android
 {
@@ -25,26 +35,23 @@ namespace Avalonia.Android
 
         private readonly double _scalingFactor = 1;
 
-        AndroidPlatform()
+        public AndroidPlatform()
+        {
+            _scalingFactor = global::Android.App.Application.Context.Resources.DisplayMetrics.ScaledDensity;
+        }
+
+        public static void Initialize()
         {
             AvaloniaLocator.CurrentMutable
                 .Bind<IClipboard>().ToTransient<ClipboardImpl>()
                 .Bind<IStandardCursorFactory>().ToTransient<CursorFactory>()
                 .Bind<IKeyboardDevice>().ToSingleton<AndroidKeyboardDevice>()
                 .Bind<IMouseDevice>().ToSingleton<AndroidMouseDevice>()
-                .Bind<IPlatformSettings>().ToConstant(this)
+                .Bind<IPlatformSettings>().ToConstant(Instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(new AndroidThreadingInterface())
                 .Bind<ISystemDialogImpl>().ToTransient<SystemDialogImpl>()
                 .Bind<ITopLevelRenderer>().ToTransient<AndroidTopLevelRenderer>()
-                .Bind<IWindowingPlatform>().ToConstant(this);
+                .Bind<IWindowingPlatform>().ToConstant(Instance);
-
-            SkiaPlatform.Initialize();
-
-            _scalingFactor = global::Android.App.Application.Context.Resources.DisplayMetrics.ScaledDensity;
-
-            
-            //we have custom Assetloader so no need to overwrite it
-            
         }
 
         public void Init(Type applicationType)