Fix more uses of T* conversion operator from scoped_refptr<T> which is now removed

ui/ozone/platform/dri/gbm_surface_factory.cc

Index: ui/ozone/platform/dri/gbm_surface_factory.cc
diff --git a/ui/ozone/platform/dri/gbm_surface_factory.cc b/ui/ozone/platform/dri/gbm_surface_factory.cc
index 509fe5f31bcac8f65730014d805308f9fdf9d019..5983688660200ae61697c1e4f1b110d14ebbadb7 100644
--- a/ui/ozone/platform/dri/gbm_surface_factory.cc
+++ b/ui/ozone/platform/dri/gbm_surface_factory.cc
@@ -174,7 +174,7 @@ scoped_refptr<ui::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(
     BufferFormat format) {
   scoped_refptr<GbmBuffer> buffer = GbmBuffer::CreateBuffer(
       drm_, device_, format, size, true);
-  if (!buffer)
+  if (!buffer.get())
     return NULL;
 
   return scoped_refptr<GbmPixmap>(new GbmPixmap(buffer));
@@ -196,7 +196,7 @@ bool GbmSurfaceFactory::ScheduleOverlayPlane(
     const gfx::Rect& display_bounds,
     const gfx::RectF& crop_rect) {
   scoped_refptr<GbmPixmap> pixmap = static_cast<GbmPixmap*>(buffer.get());
-  if (!pixmap) {
+  if (!pixmap.get()) {
     LOG(ERROR) << "ScheduleOverlayPlane passed NULL buffer.";
     return false;
   }