SigninStatusMetricsProvider factory returns a std::unique_ptr<>.

ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ios/chrome/browser/metrics/ios_chrome_metrics_service_client.h"
 
 #include <stdint.h>
 
 #include <utility>
 #include <vector>
@@ skipping 213 matching lines @@
             base::Bind(&metrics::IsCellularLogicEnabled));
     profiler_metrics_provider_ = profiler_metrics_provider.get();
     metrics_service_->RegisterMetricsProvider(
         std::move(profiler_metrics_provider));
   }
 
   metrics_service_->RegisterMetricsProvider(
       base::MakeUnique<metrics::CallStackProfileMetricsProvider>());
 
   metrics_service_->RegisterMetricsProvider(
-      base::WrapUnique(SigninStatusMetricsProvider::CreateInstance(
-          base::MakeUnique<IOSChromeSigninStatusMetricsProviderDelegate>())));
+      SigninStatusMetricsProvider::CreateInstance(
+          base::MakeUnique<IOSChromeSigninStatusMetricsProviderDelegate>()));
 
   metrics_service_->RegisterMetricsProvider(
       base::MakeUnique<MobileSessionShutdownMetricsProvider>(
           metrics_service_.get()));
 
   metrics_service_->RegisterMetricsProvider(
       base::MakeUnique<syncer::DeviceCountMetricsProvider>(
           base::Bind(&IOSChromeSyncClient::GetDeviceInfoTrackers)));
 
   metrics_service_->RegisterMetricsProvider(
@@ skipping 70 matching lines @@
 
 void IOSChromeMetricsServiceClient::OnURLOpenedFromOmnibox(OmniboxLog* log) {
   metrics_service_->OnApplicationNotIdle();
 }
 
 metrics::EnableMetricsDefault
 IOSChromeMetricsServiceClient::GetMetricsReportingDefaultState() {
   return metrics::GetMetricsReportingDefaultState(
       GetApplicationContext()->GetLocalState());
 }