Quantify instability according to the stability instrumentation

components/browser_watcher/postmortem_report_collector.cc

Index: components/browser_watcher/postmortem_report_collector.cc
diff --git a/components/browser_watcher/postmortem_report_collector.cc b/components/browser_watcher/postmortem_report_collector.cc
index 35cc7b455b39c324162f31fb73c046d88fda9e93..0d213b0013cf82969c383328ce97e742d6f11a05 100644
--- a/components/browser_watcher/postmortem_report_collector.cc
+++ b/components/browser_watcher/postmortem_report_collector.cc
@@ -63,7 +63,8 @@ PostmortemReportCollector::PostmortemReportCollector(
     : product_name_(product_name),
       version_number_(version_number),
       channel_name_(channel_name),
-      system_session_analyzer_(analyzer) {}
+      system_session_analyzer_(analyzer),
+      unclean_system_cnt_(0) {}
 
 PostmortemReportCollector::~PostmortemReportCollector() {}
 
@@ -75,6 +76,7 @@ int PostmortemReportCollector::CollectAndSubmitAllPendingReports(
   DCHECK_NE(true, debug_info_dir.empty());
   DCHECK_NE(true, debug_file_pattern.empty());
   DCHECK_NE(nullptr, report_database);
+  unclean_system_cnt_ = 0;

[Sigurður Ásgeirsson, 2017/05/15 20:18:04]

looks like rather than a member variable, you want a local that's passed into
CollectAndSubmitOneReport?

[manzagop (departed), 2017/05/17 22:31:56]

Yes! Done.

 
   // Collect the list of files to harvest.
   std::vector<FilePath> debug_files = GetDebugStateFilePaths(
@@ -103,6 +105,11 @@ int PostmortemReportCollector::CollectAndSubmitAllPendingReports(
       ++success_cnt;
   }
 
+  UMA_STABILITY_HISTOGRAM_COUNTS_100(
+      "ActivityTracker.Collect.UncleanShutdownCount", success_cnt);
+  UMA_STABILITY_HISTOGRAM_COUNTS_100(

[Sigurður Ásgeirsson, 2017/05/15 20:18:04]

is it possible to test these metrics - it'd be pretty sweet to have metrics we
can rely on ;).

[manzagop (departed), 2017/05/17 22:31:56]

I've added some histogram testing.

+      "ActivityTracker.Collect.UncleanSystemCount", unclean_system_cnt_);
+
   return success_cnt;
 }
 
@@ -256,6 +263,7 @@ void PostmortemReportCollector::RecordSystemShutdownState(
         break;
       case SystemSessionAnalyzer::UNCLEAN:
         session_state = SystemState::UNCLEAN;
+        unclean_system_cnt_++;
         break;
       case SystemSessionAnalyzer::OUTSIDE_RANGE:
         status = SYSTEM_SESSION_ANALYSIS_OUTSIDE_RANGE;