Avoid double initializing reporting_service_

components/metrics/reporting_service.cc

Index: components/metrics/reporting_service.cc
diff --git a/components/metrics/reporting_service.cc b/components/metrics/reporting_service.cc
index a541b298be8ffc829b7ba076f429ded46ffb0f29..8b96d4af2e831aec3cc74f84f9d50bf74e006059 100644
--- a/components/metrics/reporting_service.cc
+++ b/components/metrics/reporting_service.cc
@@ -43,6 +43,7 @@ ReportingService::~ReportingService() {
 
 void ReportingService::Initialize() {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!upload_scheduler_);
   log_store()->LoadPersistedUnsentLogs();
   base::Closure send_next_log_callback = base::Bind(
       &ReportingService::SendNextLog, self_ptr_factory_.GetWeakPtr());