Disable sending persistent histograms from last session by default.

components/metrics/file_metrics_provider.cc

Index: components/metrics/file_metrics_provider.cc
diff --git a/components/metrics/file_metrics_provider.cc b/components/metrics/file_metrics_provider.cc
index d5c8769f261fe874e9c7638a6dcd1eb6ea7a8593..f26af968e39cbf73dd785d48df222579d762434d 100644
--- a/components/metrics/file_metrics_provider.cc
+++ b/components/metrics/file_metrics_provider.cc
@@ -491,12 +491,6 @@ void FileMetricsProvider::OnDidCreateMetricsLog() {
 bool FileMetricsProvider::HasInitialStabilityMetrics() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  // Check if there is an experiment that disables stability metrics.
-  std::string unreported = variations::GetVariationParamValueByFeature(
-      base::kPersistentHistogramsFeature, "send_unreported_metrics");
-  if (unreported == "no")
-    sources_for_previous_run_.clear();
-
   // Measure the total time spent checking all sources as well as the time
   // per individual file. This method is called during startup and thus blocks
   // the initial showing of the browser window so it's important to know the