Immediately flush command buffer

Dotnet/Overlay/OffScreenBrowser.cs

@@ -11,6 +11,7 @@
 using SharpDX.Direct3D11;
 using System;
 using System.Threading;
+using SharpDX.Direct3D;
 using SharpDX.Mathematics.Interop;
 using Range = CefSharp.Structs.Range;
 
@@ -19,6 +20,7 @@ namespace VRCX
     public class OffScreenBrowser : ChromiumWebBrowser, IRenderHandler
     {
         private Device1 _device;
+        private DeviceMultithread _deviceMultithread;
         private Query _query;
         private Texture2D _renderTarget;
 
@@ -49,7 +51,12 @@ public OffScreenBrowser(string address, int width, int height)
         public void UpdateRender(Device device, Texture2D renderTarget)
         {
             _device = device.QueryInterface<Device1>();
+            _deviceMultithread?.Dispose();
+            _deviceMultithread = device.QueryInterfaceOrNull<DeviceMultithread>();
+            _deviceMultithread?.SetMultithreadProtected(true);
+
             _renderTarget = renderTarget;
+
             _query?.Dispose();
             _query = new Query(_device, new QueryDescription
             {
@@ -91,10 +98,11 @@ void IRenderHandler.OnAcceleratedPaint(PaintElementType type, Rect dirtyRect, Ac
 
             if (_device == null)
                 return;
-
+            
             using Texture2D cefTexture = _device.OpenSharedResource1<Texture2D>(paintInfo.SharedTextureHandle);
             _device.ImmediateContext.CopyResource(cefTexture, _renderTarget);
             _device.ImmediateContext.End(_query);
+            _device.ImmediateContext.Flush();
 
             RawBool q = _device.ImmediateContext.GetData<RawBool>(_query, AsynchronousFlags.DoNotFlush);