metrics: fix global-buffer-overflow

This fix the problem that the subscript of a global
array overflows in some cases.

BUG=chromium:326284
TEST=Unittest and suite:smoke passes.

Change-Id: I6a19d3bb18a886ee8a29b9a4df5f2b136ce57c5c
Reviewed-on: https://chromium-review.googlesource.com/178973
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
diff --git a/metrics/metrics_daemon.cc b/metrics/metrics_daemon.cc
index 1161f6c..1655fae 100644
--- a/metrics/metrics_daemon.cc
+++ b/metrics/metrics_daemon.cc
@@ -1048,7 +1048,7 @@
     // Enough active time has passed.  Do the work, and (if we succeed) see if
     // we need to do more.
     if (MemuseCallbackWork() &&
-        memuse_interval_index_ < arraysize(kMemuseIntervals)) {
+        memuse_interval_index_ < arraysize(kMemuseIntervals) - 1) {
       memuse_interval_index_++;
       ScheduleMemuseCallback(true, 0);
     }