Minor tweaks in CallStackProfileMetricsProvider

Bug: 851163
Change-Id: Ic2d0c573867b9c1e08e52febcd5211afe08c9e84
Reviewed-on: https://chromium-review.googlesource.com/1178758Reviewed-by: Mike Wittman <wittman@chromium.org>
Commit-Queue: Xi Cheng <chengx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583857}

components/metrics/call_stack_profile_metrics_provider.cc

@@ -164,10 +164,8 @@ void PendingProfiles::ResetToDefaultStateForTesting() {
 // CallStackProfileMetricsProvider.
 PendingProfiles::PendingProfiles() : collection_enabled_(true) {}
 
-// Functions to process completed profile ------------------------------------
-
 // Invoked on an arbitrary thread. Ignores the provided profile.
-void IgnoreCompletedProfile(SampledProfile profile) {}
+void IgnoreCompletedProfile(SampledProfile /*profile*/) {}
 
 }  // namespace