Persist setup metrics and have Chrome report them during UMA upload.

components/metrics/metrics_service.cc

Index: components/metrics/metrics_service.cc
diff --git a/components/metrics/metrics_service.cc b/components/metrics/metrics_service.cc
index 0b84dffbf361f48fe5554ade4e2139c78a666660..46dee9adcb995c34b761b203ed970e5e84cc45a7 100644
--- a/components/metrics/metrics_service.cc
+++ b/components/metrics/metrics_service.cc
@@ -1107,6 +1107,12 @@ void MetricsService::RecordCurrentEnvironment(MetricsLog* log) {
 
 void MetricsService::RecordCurrentHistograms() {
   DCHECK(log_manager_.current_log());
+  histogram_snapshot_manager_.StartDeltas();
+  for (size_t i = 0; i < metrics_providers_.size(); ++i) {

[grt (UTC plus 2), 2016/02/08 18:09:19]

will this work:
  for (auto& provider : metrics_providers_)
    provider->RecordHistogramSnapshots(&histogram_snapshot_manager_);

[bcwhite, 2016/02/09 21:08:46]

Seems to work.  I'll updated it elsewhere in the file, too.

+    metrics_providers_[i]->RecordHistogramSnapshots(
+        &histogram_snapshot_manager_);
+  }
+  histogram_snapshot_manager_.FinishDeltas();
 }
 
 void MetricsService::RecordCurrentStabilityHistograms() {