Use persistent memory for receiving metrics from sub-processes.

chrome/browser/metrics/chrome_metrics_service_client.cc

 // Copyright 2014 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 "chrome/browser/metrics/chrome_metrics_service_client.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 390 matching lines @@
   if (ShouldClearSavedMetrics()) {
     PrefService* local_state = g_browser_process->local_state();
     local_state->ClearPref(metrics::prefs::kMetricsInitialLogs);
     local_state->ClearPref(metrics::prefs::kMetricsOngoingLogs);
   }
 
   metrics_service_.reset(new metrics::MetricsService(
       metrics_state_manager_, this, g_browser_process->local_state()));
 
   // Gets access to persistent metrics shared by sub-processes.
+  std::unique_ptr<SubprocessMetricsProvider> subprocess_metrics_provider(
+      new SubprocessMetricsProvider());
+  subprocess_metrics_provider->EnableSubprocessTracking();
   metrics_service_->RegisterMetricsProvider(
-      std::unique_ptr<metrics::MetricsProvider>(
-          new SubprocessMetricsProvider()));
+      std::move(subprocess_metrics_provider));
 
   // Register metrics providers.
 #if defined(ENABLE_EXTENSIONS)
   metrics_service_->RegisterMetricsProvider(
       std::unique_ptr<metrics::MetricsProvider>(
           new ExtensionsMetricsProvider(metrics_state_manager_)));
 #endif
   metrics_service_->RegisterMetricsProvider(
       std::unique_ptr<metrics::MetricsProvider>(
           new metrics::NetworkMetricsProvider(
@@ skipping 369 matching lines @@
   }
 }
 
 void ChromeMetricsServiceClient::OnURLOpenedFromOmnibox(OmniboxLog* log) {
   metrics_service_->OnApplicationNotIdle();
 }
 
 bool ChromeMetricsServiceClient::IsUMACellularUploadLogicEnabled() {
   return metrics::IsCellularLogicEnabled();
 }