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

ui/ozone/platform/dri/screen_manager.cc

Index: ui/ozone/platform/dri/screen_manager.cc
diff --git a/ui/ozone/platform/dri/screen_manager.cc b/ui/ozone/platform/dri/screen_manager.cc
index f14b0869b9581f5b4931a14b5170ba9649444625..fa0ad3de760d58d160e0a7a10dea1017538dde0f 100644
--- a/ui/ozone/platform/dri/screen_manager.cc
+++ b/ui/ozone/platform/dri/screen_manager.cc
@@ -175,7 +175,7 @@ bool ScreenManager::ModesetDisplayController(
   scoped_refptr<ScanoutBuffer> buffer =
       buffer_generator_->Create(gfx::Size(mode.hdisplay, mode.vdisplay));
 
-  if (!buffer) {
+  if (!buffer.get()) {
     LOG(ERROR) << "Failed to create scanout buffer";
     return false;
   }