Send UMA stability stats in a separate UMA log on startup.

chrome/browser/metrics/metrics_service.h

Index: chrome/browser/metrics/metrics_service.h
===================================================================
--- chrome/browser/metrics/metrics_service.h	(revision 238735)
+++ chrome/browser/metrics/metrics_service.h	(working copy)
@@ -111,9 +111,21 @@
     SHUTDOWN_COMPLETE = 700,
   };
 
+  enum ReportingState {
+    REPORTING_ENABLED,
+    REPORTING_DISABLED,
+  };
+
   MetricsService();
   virtual ~MetricsService();
 
+  // Initializes metrics recording state. Updates various bookkeeping values in
+  // prefs and sets up the scheduler. This is a separate function rather than
+  // being done by the constructor so that field trials could be created before
+  // this is run. Takes |reporting_state| parameter which specifies whether UMA
+  // is enabled.
+  void InitializeMetricsRecordingState(ReportingState reporting_state);
+
   // Starts the metrics system, turning on recording and uploading of metrics.
   // Should be called when starting up with metrics enabled, or when metrics
   // are turned on.
@@ -153,7 +165,7 @@
   // because this method may need to be called before the MetricsService needs
   // to be started.
   scoped_ptr<const base::FieldTrial::EntropyProvider> CreateEntropyProvider(
-      bool reporting_will_be_enabled);
+      ReportingState reporting_state);
 
   // Force the client ID to be generated. This is useful in case it's needed
   // before recording.
@@ -253,12 +265,13 @@
   // The MetricsService has a lifecycle that is stored as a state.
   // See metrics_service.cc for description of this lifecycle.
   enum State {
-    INITIALIZED,            // Constructor was called.
-    INIT_TASK_SCHEDULED,    // Waiting for deferred init tasks to complete.
-    INIT_TASK_DONE,         // Waiting for timer to send initial log.
-    INITIAL_LOG_READY,      // Initial log generated, and waiting for reply.
-    SENDING_OLD_LOGS,       // Sending unsent logs from previous session.
-    SENDING_CURRENT_LOGS,   // Sending standard current logs as they acrue.
+    INITIALIZED,                    // Constructor was called.
+    INIT_TASK_SCHEDULED,            // Waiting for deferred init task to finish.
+    INIT_TASK_DONE,                 // Waiting for timer to send initial log.
+    SENDING_INITIAL_STABILITY_LOG,  // Initial stability log being sent.
+    SENDING_INITIAL_METRICS_LOG,    // Initial metrics log being sent.
+    SENDING_OLD_LOGS,               // Sending unsent logs from last session.
+    SENDING_CURRENT_LOGS,           // Sending ongoing logs as they accrue.
   };
 
   enum ShutdownCleanliness {
@@ -349,7 +362,7 @@
   void HandleIdleSinceLastTransmission(bool in_idle);
 
   // Set up client ID, session ID, etc.
-  void InitializeMetricsState();
+  void InitializeMetricsState(ReportingState reporting_state);
 
   // Generates a new client ID to use to identify self to metrics server.
   static std::string GenerateClientID();
@@ -393,9 +406,15 @@
   // (depending on |state_|), and stages it for upload.
   void StageNewLog();
 
-  // Record stats, client ID, Session ID, etc. in a special "first" log.
-  void PrepareInitialLog();
+  // Prepares the initial stability log, based on the saved system profile from
+  // a previous session with updated stability stats (only) and stages it for
+  // upload.

[Ilya Sherman, 2013/12/07 06:51:54]

nit: Sorry to super nitpick, but I still find this comment not entirely clear. 
A suggested rephrasing, feel free to further refine:

"Prepares the initial stability log, which is only logged when the previous run
of Chrome crashed.  This log contains any stability metrics left over from that
previous run, and only these stability metrics.  It uses the system profile from
the previous session."

[Alexei Svitkine (slow), 2013/12/09 21:17:02]

Done.

+  void PrepareInitialStabilityLog();
 
+  // Prepares the initial metrics log, which includes startup histograms and
+  // profiler data, as well as incremental stability-related metrics.
+  void PrepareInitialMetricsLog(MetricsLog::LogType log_type);
+
   // Uploads the currently staged log (which must be non-null).
   void SendStagedLog();
 
@@ -487,8 +506,10 @@
   // Google Update statistics, which were retrieved on a blocking pool thread.
   GoogleUpdateMetrics google_update_metrics_;
 
-  // The initial log, used to record startup metrics.
-  scoped_ptr<MetricsLog> initial_log_;
+  // The initial metrics log, used to record startup metrics (histograms and
+  // profiler data). Note that if a crash occurred in the previous session, an
+  // initial stability log may be sent before this.
+  scoped_ptr<MetricsLog> initial_metrics_log_;
 
   // The outstanding transmission appears as a URL Fetch operation.
   scoped_ptr<net::URLFetcher> current_fetch_;