CrOS: Log violations of GLX_OML_sync_control spec.

ui/gl/vsync_provider.cc

Index: ui/gl/vsync_provider.cc
diff --git a/ui/gl/vsync_provider.cc b/ui/gl/vsync_provider.cc
index 0bf29eb1cd8692c32ff641601023ab827ea96611..9383145222aa5c627c3a3e6df2e56a297033f9b6 100644
--- a/ui/gl/vsync_provider.cc
+++ b/ui/gl/vsync_provider.cc
@@ -65,9 +65,12 @@ void SyncControlVSyncProvider::GetVSyncParameters(
 
   // Both Intel and Mali drivers will return TRUE for GetSyncValues
   // but a value of 0 for MSC if they cannot access the CRTC data structure
-  // associated with the surfrace.
-  if (media_stream_counter == 0)
+  // associated with the surfrace. crbug.com/231945
+  if (media_stream_counter == 0) {
+    LOG(ERROR) << "glXGetSyncValuesOML should not return TRUE with a "
+               << "media stream counter of 0.";
     return;
+  }
 
   struct timespec real_time;
   struct timespec monotonic_time;