Support experiment configurations with/without stability metrics.

components/metrics/metrics_service.cc

Index: components/metrics/metrics_service.cc
diff --git a/components/metrics/metrics_service.cc b/components/metrics/metrics_service.cc
index 5c9448987ab9b42348f2ed6a8b0743936542dacb..ed15edfb11bb547c5fc780bef30a0d642958ea24 100644
--- a/components/metrics/metrics_service.cc
+++ b/components/metrics/metrics_service.cc
@@ -914,12 +914,11 @@ void MetricsService::SendNextLog() {
 
 bool MetricsService::ProvidersHaveInitialStabilityMetrics() {
   // Check whether any metrics provider has initial stability metrics.
-  for (MetricsProvider* provider : metrics_providers_) {
-    if (provider->HasInitialStabilityMetrics())
-      return true;
-  }
+  bool has_stability_metrics = false;
+  for (MetricsProvider* provider : metrics_providers_)
+    has_stability_metrics |= provider->HasInitialStabilityMetrics();

[Alexei Svitkine (slow), 2016/11/24 21:27:58]

Please add a comment above why this doesn't do an early return.

[bcwhite, 2016/11/25 18:51:58]

Done.

 
-  return false;
+  return has_stability_metrics;
 }
 
 bool MetricsService::PrepareInitialStabilityLog(