Flush UKM metrics when backgrounded on Android and iOS.

chrome/browser/android/metrics/uma_session_stats.cc

Index: chrome/browser/android/metrics/uma_session_stats.cc
diff --git a/chrome/browser/android/metrics/uma_session_stats.cc b/chrome/browser/android/metrics/uma_session_stats.cc
index 854f9fc6614f54716800ddf3b2e07130f4314fb5..8e82df4f11b4814fca49ba520c997ccbf2fd1de6 100644
--- a/chrome/browser/android/metrics/uma_session_stats.cc
+++ b/chrome/browser/android/metrics/uma_session_stats.cc
@@ -20,6 +20,7 @@
 #include "components/metrics/metrics_service.h"
 #include "components/metrics_services_manager/metrics_services_manager.h"
 #include "components/prefs/pref_service.h"
+#include "components/ukm/ukm_service.h"
 #include "components/variations/metrics_util.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
@@ -48,11 +49,15 @@ void UmaSessionStats::UmaResumeSession(JNIEnv* env,
   if (active_session_count_ == 0) {
     session_start_time_ = base::TimeTicks::Now();
 
-    // Tell the metrics service that the application resumes.
+    // Tell the metrics services that the application resumes.
     metrics::MetricsService* metrics = g_browser_process->metrics_service();
     if (metrics) {
       metrics->OnAppEnterForeground();
     }
+    ukm::UkmService* ukm_service = g_browser_process->ukm_service();
+    if (ukm_service) {

[Alexei Svitkine (slow), 2017/03/01 22:56:13]

Nit: No {}s

Remove them from metrics service case above and below as well.

[Bryan McQuade, 2017/03/01 23:06:50]

Done

+      ukm_service->OnAppEnterForeground();
+    }
   }
   ++active_session_count_;
 }
@@ -70,11 +75,15 @@ void UmaSessionStats::UmaEndSession(JNIEnv* env,
     UMA_HISTOGRAM_LONG_TIMES("Session.TotalDuration", duration);
 
     DCHECK(g_browser_process);
-    // Tell the metrics service it was cleanly shutdown.
+    // Tell the metrics services they were cleanly shutdown.
     metrics::MetricsService* metrics = g_browser_process->metrics_service();
     if (metrics) {
       metrics->OnAppEnterBackground();
     }
+    ukm::UkmService* ukm_service = g_browser_process->ukm_service();
+    if (ukm_service) {
+      ukm_service->OnAppEnterBackground();
+    }
   }
 }