Switch DRM platform to using a separate thread

ui/ozone/platform/drm/gpu/gbm_surface.h

Index: ui/ozone/platform/drm/gpu/gbm_surface.h
diff --git a/ui/ozone/platform/drm/gpu/gbm_surface.h b/ui/ozone/platform/drm/gpu/gbm_surface.h
index 89d84543e551b2c4ea7cddd7de2bbe1500daefdd..880323e5855a3461fd207dc28792ffc81a2a8462 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surface.h
+++ b/ui/ozone/platform/drm/gpu/gbm_surface.h
@@ -17,7 +17,6 @@ struct gbm_surface;
 namespace ui {
 
 class DrmBuffer;
-class DrmWindow;
 class GbmDevice;
 
 // Extends the GBM surfaceless functionality and adds an implicit surface for
@@ -26,7 +25,8 @@ class GbmDevice;
 // surface and is updated via an EGLSurface.
 class GbmSurface : public GbmSurfaceless {
  public:
-  GbmSurface(DrmWindow* window, const scoped_refptr<GbmDevice>& gbm);
+  GbmSurface(scoped_ptr<DrmWindowProxy> window,
+             const scoped_refptr<GbmDevice>& gbm);
   ~GbmSurface() override;
 
   bool Initialize();