[Ozone-GBM] Migrate GBM buffers to use the ScanoutBuffer interface

ui/ozone/platform/dri/gbm_surface.h

Index: ui/ozone/platform/dri/gbm_surface.h
diff --git a/ui/ozone/platform/dri/gbm_surface.h b/ui/ozone/platform/dri/gbm_surface.h
index 8b8dffcad8a88fb71ee98dde4c5e4ea90ee71f98..a8c078a5523d156aab76a71e4a2728e33e5c5fc2 100644
--- a/ui/ozone/platform/dri/gbm_surface.h
+++ b/ui/ozone/platform/dri/gbm_surface.h
@@ -18,6 +18,7 @@ namespace ui {
 
 class DriBuffer;
 class DriWrapper;
+class GbmBufferBase;
 
 // Implement the ScanoutSurface interface on top of GBM (Generic Buffer
 // Manager). GBM provides generic access to hardware accelerated surfaces which
@@ -49,7 +50,7 @@ class GbmSurface : public ScanoutSurface {
 
   // Backing GBM buffers. One is the current front buffer. The other is the
   // current backbuffer that is pending scan out.
-  gbm_bo* buffers_[2];
+  scoped_refptr<GbmBufferBase> buffers_[2];
 
   // Index to the front buffer.
   int front_buffer_;