Fixing typo in metrics log

metrics_log.cc had a typo, fixed in this CL :)

Change-Id: I51838078d29ff7747c4a208b6822ed1fac763b30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2350153
Commit-Queue: Joshua Berenhaus <joshber@microsoft.com>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797022}

components/metrics/metrics_log.cc

@@ -321,7 +321,7 @@ const SystemProfileProto& MetricsLog::RecordEnvironment(
   //
   // The |has_environment| case will happen on the very first log, where we
   // call RecordEnvironment() in order to persist the system profile in the
-  // persistent hitograms .pma file.
+  // persistent histograms .pma file.
   if (has_environment_) {
     uma_proto_.clear_system_profile();
     MetricsLog::RecordCoreSystemProfile(client_,