base: Change DCHECK_IS_ON to a macro DCHECK_IS_ON().

base/tracked_objects.h

Index: base/tracked_objects.h
diff --git a/base/tracked_objects.h b/base/tracked_objects.h
index eb38df6b8d675d372bb9bce4803d99fed825e856..5196f192bb1ec90cf15018c2655bd420460cf822 100644
--- a/base/tracked_objects.h
+++ b/base/tracked_objects.h
@@ -749,7 +749,7 @@ class BASE_EXPORT TaskStopwatch {
   // duration of this stopwatch.
   TaskStopwatch* parent_;
 
-#if DCHECK_IS_ON
+#if DCHECK_IS_ON()
   // State of the stopwatch. Stopwatch is first constructed in a created state
   // state, then is optionally started/stopped, then destructed.
   enum { CREATED, RUNNING, STOPPED } state_;