Readability review.

Review URL: http://codereview.chromium.org/2729018
diff --git a/metrics/counter_mock.h b/metrics/counter_mock.h
index 22327ac..baa97b0 100644
--- a/metrics/counter_mock.h
+++ b/metrics/counter_mock.h
@@ -24,3 +24,4 @@
 }  // namespace chromeos_metrics
 
 #endif  // METRICS_COUNTER_MOCK_H_
+