add unity doc.

unity/PICO-Unity-Integration-SDK-release_3.4.0/Enterprise/Scripts/Interfaces/LongCallback.cs

@@ -0,0 +1,26 @@
+using System;
+using UnityEngine;
+
+namespace Unity.XR.PICO.TOBSupport
+{
+    public class LongCallback : AndroidJavaProxy
+    {
+        public Action<long> mCallback;
+
+        public LongCallback(Action<long> callback) : base("com.picoxr.tobservice.interfaces.LongCallback")
+        {
+            mCallback = callback;
+        }
+
+        public void CallBack(long var1)
+        {
+            PXR_EnterpriseTools.QueueOnMainThread(() =>
+            {
+                if (mCallback != null)
+                {
+                    mCallback(var1);
+                }
+            });
+        }
+    }
+}