diff --git a/cc/scheduler/delay_based_time_source.h b/cc/scheduler/delay_based_time_source.h
index 9f670d1..ea03f9d 100644
--- a/cc/scheduler/delay_based_time_source.h
+++ b/cc/scheduler/delay_based_time_source.h
@@ -95,7 +95,9 @@
   DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSource);
 };
 
-// DelayBasedTimeSource uses base::TimeTicks::HighResNow as its timebase.
+// DelayBasedTimeSource that once used base::TimeTicks::HighResNow as its time
+// source, but is now a no-op.
+// TODO(brianderson): Remove along with gfx::/FrameTime.http://crbug.com/447329
 class DelayBasedTimeSourceHighRes : public DelayBasedTimeSource {
  public:
   static scoped_refptr<DelayBasedTimeSourceHighRes> Create(