Fix black screen when switching primary display without bounds change

ui/ozone/platform/drm/gpu/drm_buffer.cc

Index: ui/ozone/platform/drm/gpu/drm_buffer.cc
diff --git a/ui/ozone/platform/drm/gpu/drm_buffer.cc b/ui/ozone/platform/drm/gpu/drm_buffer.cc
index 24981a52eac0c29f2ff3208389c64bcdc8116e9e..3acbe62c93e76eebf296c0188185d3a2c1dad08b 100644
--- a/ui/ozone/platform/drm/gpu/drm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/drm_buffer.cc
@@ -106,6 +106,10 @@ gfx::Size DrmBuffer::GetSize() const {
   return gfx::Size(surface_->width(), surface_->height());
 }
 
+const DrmDevice* DrmBuffer::GetDrmDevice() const {
+  return drm_.get();
+}
+
 bool DrmBuffer::RequiresGlFinish() const {
   return false;
 }