Reporting: Add histograms.

net/reporting/reporting_garbage_collector.cc

Index: net/reporting/reporting_garbage_collector.cc
diff --git a/net/reporting/reporting_garbage_collector.cc b/net/reporting/reporting_garbage_collector.cc
index 50e6d562057c507d7491b37361b9fdbacbe71548..188cda1e46c1569f8f9f54d7e542c4947bb131fc 100644
--- a/net/reporting/reporting_garbage_collector.cc
+++ b/net/reporting/reporting_garbage_collector.cc
@@ -57,17 +57,21 @@ class ReportingGarbageCollectorImpl : public ReportingGarbageCollector,
     std::vector<const ReportingReport*> all_reports;
     context_->cache()->GetReports(&all_reports);
 
-    std::vector<const ReportingReport*> reports_to_remove;
+    std::vector<const ReportingReport*> failed_reports;
+    std::vector<const ReportingReport*> expired_reports;
     for (const ReportingReport* report : all_reports) {
-      if (now - report->queued >= policy.max_report_age ||
-          report->attempts >= policy.max_report_attempts) {
-        reports_to_remove.push_back(report);
-      }
+      if (report->attempts >= policy.max_report_attempts)
+        failed_reports.push_back(report);
+      else if (now - report->queued >= policy.max_report_age)
+        expired_reports.push_back(report);
     }
 
     // Don't restart the timer on the garbage collector's own updates.
     context_->RemoveObserver(this);
-    context_->cache()->RemoveReports(reports_to_remove);
+    context_->cache()->RemoveReports(failed_reports,
+                                     ReportingReport::Outcome::ERASED_FAILED);
+    context_->cache()->RemoveReports(expired_reports,
+                                     ReportingReport::Outcome::ERASED_EXPIRED);
     context_->AddObserver(this);
   }