Wire up cursor proxy on MUS

ui/ozone/platform/drm/ozone_platform_gbm.cc

Index: ui/ozone/platform/drm/ozone_platform_gbm.cc
diff --git a/ui/ozone/platform/drm/ozone_platform_gbm.cc b/ui/ozone/platform/drm/ozone_platform_gbm.cc
index 7ebc29510af0018ddf15d85344fe5b57d5f165a9..9ccb57a70f9847794af6a3e1add8215253d334e6 100644
--- a/ui/ozone/platform/drm/ozone_platform_gbm.cc
+++ b/ui/ozone/platform/drm/ozone_platform_gbm.cc
@@ -149,6 +149,7 @@ class OzonePlatformGbm : public OzonePlatform {
       gl_api_loader_.reset(new GlApiLoader());
       mus_thread_proxy_.reset(new MusThreadProxy());
       adapter = mus_thread_proxy_.get();
+      cursor_->SetDrmCursorProxy(mus_thread_proxy_.get());
     } else {
       gpu_platform_support_host_.reset(
           new DrmGpuPlatformSupportHost(cursor_.get()));