Allow MetricsProviders to request an initial stability log.

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 001e66a42c6330f55a673840983bf24570454c97..510571f2c69888598d663d454338c5e6f57f3b04 100644
--- a/components/metrics/metrics_provider.h
+++ b/components/metrics/metrics_provider.h
@@ -33,6 +33,10 @@ class MetricsProvider {
   virtual void ProvideSystemProfileMetrics(
       SystemProfileProto* system_profile_proto) {}
 
+  // Called once at startup to see whether this provider has stability events
+  // to share.
+  virtual bool HasStabilityMetrics() { return false; }
+
   // Provides additional stability metrics. Stability metrics can be provided
   // directly into |stability_proto| fields or by logging stability histograms
   // via the UMA_STABILITY_HISTOGRAM_ENUMERATION() macro.