Starting a refactor to allow adding metrics on upload.

components/metrics/metrics_provider.h

Index: components/metrics/metrics_provider.h
diff --git a/components/metrics/metrics_provider.h b/components/metrics/metrics_provider.h
index 9daaaafce245636ebc9107eee945d49940a06354..7a1356296d746edbae6e95681cbe767c886acb6d 100644
--- a/components/metrics/metrics_provider.h
+++ b/components/metrics/metrics_provider.h
@@ -29,6 +29,9 @@ class MetricsProvider {
   // Called when metrics recording has been disabled.
   virtual void OnRecordingDisabled();
 
+  // Called right before metrics are uploaded.
+  virtual void OnCollectFinalMetrics();
+
   // Provides additional metrics into the system profile.
   virtual void ProvideSystemProfileMetrics(
       SystemProfileProto* system_profile_proto);