Switch DRM platform to using a separate thread

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

Index: ui/ozone/platform/drm/gpu/gbm_surfaceless.h
diff --git a/ui/ozone/platform/drm/gpu/gbm_surfaceless.h b/ui/ozone/platform/drm/gpu/gbm_surfaceless.h
index 7fa079b5a4c22d4379ead5951f3999451cdd85bc..2db7feb9b661014aed4ab0aa70f2e7c9b14489ad 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surfaceless.h
+++ b/ui/ozone/platform/drm/gpu/gbm_surfaceless.h
@@ -5,15 +5,18 @@
 #ifndef UI_OZONE_PLATFORM_DRM_GPU_GBM_SURFACELESS_H_
 #define UI_OZONE_PLATFORM_DRM_GPU_GBM_SURFACELESS_H_
 
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "ui/gfx/native_widget_types.h"
 #include "ui/ozone/public/surface_ozone_egl.h"
 
 namespace gfx {
 class Size;
-}  // namespace gfx
+}
 
 namespace ui {
 
-class DrmDeviceManager;
+class DrmThread;
 class DrmWindow;
 
 // In surfaceless mode drawing and displaying happens directly through
@@ -22,7 +25,7 @@ class DrmWindow;
 // presentation.
 class GbmSurfaceless : public SurfaceOzoneEGL {
  public:
-  GbmSurfaceless(DrmWindow* window, DrmDeviceManager* drm_device_manager);
+  GbmSurfaceless(gfx::AcceleratedWidget widget, DrmThread* drm_thread);
   ~GbmSurfaceless() override;
 
   // SurfaceOzoneEGL:
@@ -34,8 +37,9 @@ class GbmSurfaceless : public SurfaceOzoneEGL {
   bool IsUniversalDisplayLinkDevice() override;
 
  protected:
-  DrmWindow* window_;
-  DrmDeviceManager* drm_device_manager_;
+  gfx::AcceleratedWidget widget_;
+  DrmThread* drm_thread_;
+  base::WeakPtr<DrmWindow> window_;
 
   DISALLOW_COPY_AND_ASSIGN(GbmSurfaceless);
 };