Decouple Metrics Initialization from IO Thread Initialization

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 b896440857adfc4bfc2e4940519f158a85330a87..425535cd6d1f9aa94a8d3a9f234e2c19365a56fd 100644
--- a/components/metrics/metrics_service.cc
+++ b/components/metrics/metrics_service.cc
@@ -536,14 +536,15 @@ void MetricsService::PushExternalLog(const std::string& log) {
   log_manager_.StoreLog(log, MetricsLog::ONGOING_LOG);
 }
 
-UpdateUsagePrefCallbackType MetricsService::GetDataUseForwardingCallback() {
+void MetricsService::UpdateMetricsUsagePrefs(const std::string& service_name,
+                                             int message_size,
+                                             bool is_cellular) {
   DCHECK(IsSingleThreaded());
-
   if (data_use_tracker_) {
-    return data_use_tracker_->GetDataUseForwardingCallback(
-        base::ThreadTaskRunnerHandle::Get());
+    data_use_tracker_->UpdateMetricsUsagePrefs(service_name,
+                                               message_size,
+                                               is_cellular);
   }
-  return UpdateUsagePrefCallbackType();
 }
 
 void MetricsService::MergeHistogramDeltas() {