Notify page load metrics when the app enters the background.

chrome/browser/metrics/chrome_metrics_service_client.cc

Index: chrome/browser/metrics/chrome_metrics_service_client.cc
diff --git a/chrome/browser/metrics/chrome_metrics_service_client.cc b/chrome/browser/metrics/chrome_metrics_service_client.cc
index 8bb2f6c2e948bd44dead435b390dc26614fb2ba7..25cf5f31d0775d09cdf5fcfe29faf15c5685f869 100644
--- a/chrome/browser/metrics/chrome_metrics_service_client.cc
+++ b/chrome/browser/metrics/chrome_metrics_service_client.cc
@@ -29,6 +29,7 @@
 #include "chrome/browser/metrics/chrome_stability_metrics_provider.h"
 #include "chrome/browser/metrics/https_engagement_metrics_provider.h"
 #include "chrome/browser/metrics/metrics_reporting_state.h"
+#include "chrome/browser/metrics/page_load_metrics_provider.h"
 #include "chrome/browser/metrics/subprocess_metrics_provider.h"
 #include "chrome/browser/metrics/time_ticks_experiment_win.h"
 #include "chrome/browser/sync/chrome_sync_client.h"
@@ -528,6 +529,9 @@ void ChromeMetricsServiceClient::Initialize() {
       std::unique_ptr<metrics::MetricsProvider>(
           new HttpsEngagementMetricsProvider()));
 
+  metrics_service_->RegisterMetricsProvider(
+      std::unique_ptr<metrics::MetricsProvider>(new PageLoadMetricsProvider()));
+
   // Clear stability metrics if it is the first time cellular upload logic
   // should apply to avoid sudden bulk uploads. It needs to be done after all
   // providers are registered.