[Cleanup] Migrate ExternalMetrics to use the Task Scheduler.

chromecast/browser/metrics/external_metrics.h

Index: chromecast/browser/metrics/external_metrics.h
diff --git a/chromecast/browser/metrics/external_metrics.h b/chromecast/browser/metrics/external_metrics.h
index 9e48da4902df63bf4d00798769f290ef1606d997..e96c60daf6735f594985e0c62a925892c4fb3e83 100644
--- a/chromecast/browser/metrics/external_metrics.h
+++ b/chromecast/browser/metrics/external_metrics.h
@@ -62,6 +62,9 @@ class ExternalMetrics {
   // Calls CollectEvents and reschedules a future collection.
   void CollectEventsAndReschedule();
 
+  // Schedules a future collection.
+  void ScheduleCollection();
+
   // Reference to stability metrics provider, for reporting external crashes.
   CastStabilityMetricsProvider* const stability_provider_;