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

components/metrics/metrics_service.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
 //
 // A MetricsService instance is typically created at application startup.  It is
@@ skipping 1089 matching lines @@
 
 void MetricsService::RecordCurrentEnvironment(MetricsLog* log) {
   std::vector<variations::ActiveGroupId> synthetic_trials;
   GetSyntheticFieldTrialsOlderThan(log->creation_time(), &synthetic_trials);
   log->RecordEnvironment(metrics_providers_.get(), synthetic_trials,
                          GetInstallDate(), GetMetricsReportingEnabledDate());
 }
 
 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() {
   DCHECK(log_manager_.current_log());
   // "true" indicates that StatisticsRecorder should include histograms in
   // persistent storage.
   histogram_snapshot_manager_.PrepareDeltas(
       base::StatisticsRecorder::begin(true), base::StatisticsRecorder::end(),
       base::Histogram::kNoFlags, base::Histogram::kUmaStabilityHistogramFlag);
 }
@@ skipping 27 matching lines @@
                  base::Time::Now().ToTimeT());
 }
 
 void MetricsService::SkipAndDiscardUpload() {
   log_manager_.DiscardStagedLog();
   scheduler_->UploadCancelled();
   log_upload_in_progress_ = false;
 }
 
 }  // namespace metrics