Log operator code histogram on new metric log

chrome/browser/metrics/metrics_service.cc

Index: chrome/browser/metrics/metrics_service.cc
diff --git a/chrome/browser/metrics/metrics_service.cc b/chrome/browser/metrics/metrics_service.cc
index 55c13212d1436296e19024622d75a1e82161f762..e3da5fe98b16f79d4a2bbfdd5f69de402b80c15b 100644
--- a/chrome/browser/metrics/metrics_service.cc
+++ b/chrome/browser/metrics/metrics_service.cc
@@ -1120,6 +1120,7 @@ void MetricsService::ReceivedProfilerData(
   if (!initial_metrics_log_.get()) {
     initial_metrics_log_.reset(
         new MetricsLog(client_id_, session_id_, MetricsLog::ONGOING_LOG));
+    NotifyOnNewMetricsLog();
   }
 
   initial_metrics_log_->RecordProfilerData(process_data, process_type);
@@ -1206,6 +1207,22 @@ int MetricsService::GetLowEntropySource() {
   return low_entropy_source_;
 }
 
+void MetricsService::AddMetricsLogObserver(MetricsLogObserver* observer) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  metrics_log_observers_.AddObserver(observer);
+}
+
+void MetricsService::RemoveMetricsLogObserver(MetricsLogObserver* observer) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  metrics_log_observers_.RemoveObserver(observer);

[bengr, 2014/05/06 17:14:39]

Are the observers guaranteed to outlive the MetricsService?

[bolian, 2014/05/06 18:00:08]

For the current usage, Yes.
If not in the future, observers should remove themselves before die.

+}
+
+void MetricsService::NotifyOnNewMetricsLog() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  FOR_EACH_OBSERVER(
+      MetricsLogObserver, metrics_log_observers_, OnNewMetricsLog());
+}
+
 // static
 std::string MetricsService::GenerateClientID() {
   return base::GenerateGUID();
@@ -1245,6 +1262,7 @@ void MetricsService::OpenNewLog() {
 
   log_manager_.BeginLoggingWithLog(
       new MetricsLog(client_id_, session_id_, MetricsLog::ONGOING_LOG));
+  NotifyOnNewMetricsLog();
   if (state_ == INITIALIZED) {
     // We only need to schedule that run once.
     state_ = INIT_TASK_SCHEDULED;
@@ -1542,6 +1560,7 @@ void MetricsService::PrepareInitialStabilityLog() {
   scoped_ptr<MetricsLog> initial_stability_log(
       new MetricsLog(client_id_, session_id_,
                      MetricsLog::INITIAL_STABILITY_LOG));
+  NotifyOnNewMetricsLog();
   if (!initial_stability_log->LoadSavedEnvironmentFromPrefs())
     return;
   initial_stability_log->RecordStabilityMetrics(base::TimeDelta(),
@@ -2082,3 +2101,19 @@ bool MetricsServiceHelper::IsCrashReportingEnabled() {
   return false;
 #endif
 }
+
+void MetricsServiceHelper::AddMetricsLogObserver(
+    MetricsLogObserver* observer) {
+  MetricsService* metrics_service = g_browser_process->metrics_service();
+  if (metrics_service != NULL) {

[bengr, 2014/05/06 17:14:39]

When would this be null?

[bolian, 2014/05/06 18:00:08]

Just as a safety check before dereferring it. In theory, an observer could call
MetricsServiceHelper::AddMetricsLogObserver before the metrics service created.
But not for this CL. 

+    metrics_service->AddMetricsLogObserver(observer);
+  }
+}
+
+void MetricsServiceHelper::RemoveMetricsLogObserver(
+    MetricsLogObserver* observer) {
+  MetricsService* metrics_service = g_browser_process->metrics_service();
+  if (metrics_service != NULL) {
+    metrics_service->RemoveMetricsLogObserver(observer);
+  }
+}