Correct comments for kMaxPendingProfiles

Bug: 903972
Change-Id: Iba29af4d63e0e8dc68c728d0965e22c11bed8653
Reviewed-on: https://chromium-review.googlesource.com/c/1343354Reviewed-by: Mike Wittman <wittman@chromium.org>
Commit-Queue: Xi Cheng <chengx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609535}

components/metrics/call_stack_profile_metrics_provider.cc

@@ -19,11 +19,11 @@ namespace metrics {
 
 namespace {
 
-// Cap the number of pending profiles to avoid excessive memory usage when
-// profile uploads are delayed (e.g. due to being offline). Capping at this
-// threshold loses approximately 0.5% of profiles on canary and dev.
-// TODO(chengx): Remove this threshold after moving to a more memory-efficient
-// profile representation.
+// Cap the number of pending profiles to avoid excessive performance overhead
+// due to profile deserialization when profile uploads are delayed (e.g. due to
+// being offline). Capping at this threshold loses approximately 0.5% of
+// profiles on canary and dev.
+// TODO(chengx): Remove this threshold after crbug.com/903972 is fixed.
 const size_t kMaxPendingProfiles = 1250;
 
 // PendingProfiles ------------------------------------------------------------