iioservice: include base/timer/timer.h explicitly

For base::RepeatingTimer.

BUG=b:228144902
TEST=FEATURES=test emerge-scarlet iioservice

Change-Id: I876455d382a2c8d529f4d64cc9b233a15877daad
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/3640748
Auto-Submit: Grace Cham <hscham@chromium.org>
Reviewed-by: Cheng-Hao Yang <chenghaoyang@chromium.org>
Tested-by: Cheng-Hao Yang <chenghaoyang@chromium.org>
Tested-by: Grace Cham <hscham@chromium.org>
Commit-Queue: Grace Cham <hscham@chromium.org>
diff --git a/iioservice/daemon/sensor_metrics.h b/iioservice/daemon/sensor_metrics.h
index 35d2112..fbfba5e 100644
--- a/iioservice/daemon/sensor_metrics.h
+++ b/iioservice/daemon/sensor_metrics.h
@@ -11,6 +11,7 @@
 #include <vector>
 
 #include <base/time/time.h>
+#include <base/timer/timer.h>
 #include <metrics/metrics_library.h>
 
 #include "iioservice/include/export.h"