add test sample

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/MobileTouchSample.cs

+using System;
+using System.Collections.Generic;
+using uiwidgets;
+using Unity.UIWidgets.engine;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using UnityEngine;
+using UnityEngine.Networking;
+using Image = Unity.UIWidgets.widgets.Image;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample
+{
+    public class MobileTouchSample : UIWidgetsPanel
+    {
+        protected override void main()
+        {
+            ui_.runApp(new MaterialApp(
+                title: "Http Request Sample",
+                home: new Scaffold(
+                    body: new MobileTouchWidget()
+                )
+            ));
+        }
+    }
+
+    public class MobileTouchWidget : StatefulWidget
+    {
+        public MobileTouchWidget(Key key = null) : base(key)
+        {
+        }
+
+        public override State createState()
+        {
+            return new MobileTouchWidgetState();
+        }
+    }
+
+    class MobileTouchWidgetState : State<MobileTouchWidget>
+    {
+        private float scale = 1;
+        private int frameNo = 0;
+        private float rotation = 0;
+
+        public override Widget build(BuildContext context)
+        {
+            return new Column(
+                crossAxisAlignment: CrossAxisAlignment.center,
+                children: new List<Widget>()
+                {
+                    new Text("Frame: " + frameNo),
+                    new Text("Scale: " + scale),
+                    new Text("Rotation: " + rotation),
+                    new GestureDetector(
+                        child: new Container(height: 300, color: Colors.blue),
+                        onScaleStart: details => { },
+                        onScaleUpdate: details =>
+                        {
+                            scale = details.scale;
+                            rotation = details.rotation;
+                            frameNo += 1;
+                            setState(() => { });
+                        },
+                        onScaleEnd: details => { }
+                    )
+                });
+        }
+    }
+}