[M102] Add a metric for the extended browser crash monitoring duration.

(cherry picked from commit 49058f9)

Bug: 1321465
Change-Id: I808216e2d9fe5afe36ff999d0421b771a07e49a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3615364
Reviewed-by: Siddhartha S <ssid@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#998717}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3629706
Cr-Commit-Position: refs/branch-heads/5005@{#494}
Cr-Branched-From: 5b4d945-refs/heads/main@{#992738}

components/metrics/clean_exit_beacon.cc

@@ -366,6 +366,11 @@ void CleanExitBeacon::WriteBeaconValue(bool exited_cleanly,
   if (is_extended_safe_mode) {
     DCHECK_EQ(group_name, kEnabledGroup);
     DCHECK(!exited_cleanly);
+
+#if BUILDFLAG(IS_ANDROID)
+    extended_monitoring_stage_start_time_ = base::TimeTicks::Now();
+#endif
+
     SCOPED_UMA_HISTOGRAM_TIMER_MICROS(
         "Variations.ExtendedSafeMode.WritePrefsTime");
     // The beacon value is written to disk synchronously twice during
@@ -390,6 +395,21 @@ void CleanExitBeacon::WriteBeaconValue(bool exited_cleanly,
   } else {
     local_state_->SetBoolean(prefs::kStabilityExitedCleanly, exited_cleanly);
     local_state_->CommitPendingWrite();  // Schedule a write.
+#if BUILDFLAG(IS_ANDROID)
+    if (!extended_monitoring_stage_start_time_.is_null()) {
+      // The time exists, so this is the transition from the extended browser
+      // crash monitoring stage to the status quo stage. Only Extended
+      // Variations Safe Mode enabled-group clients have the extended monitoring
+      // stage.
+      // TODO(crbug/1321989): Clean up this metric and
+      // |extended_monitoring_stage_start_time_| once Android Chrome
+      // stakeholders have enough data on the duration.
+      base::UmaHistogramLongTimes(
+          "UMA.CleanExitBeacon.ExtendedMonitoringStageDuration",
+          base::TimeTicks::Now() - extended_monitoring_stage_start_time_);
+      extended_monitoring_stage_start_time_ = base::TimeTicks();  // Null time.
+    }
+#endif  // BUILDFLAG(IS_ANDROID)
     if (group_name == kEnabledGroup) {
       // Clients in this group write to the Variations Safe Mode file whenever
       // |kStabilityExitedCleanly| is updated. The file is kept in sync with the

components/metrics/clean_exit_beacon.h

@@ -196,6 +196,12 @@ class CleanExitBeacon {
   static void ResetUserDefaultsBeacon();
 #endif  // BUILDFLAG(IS_IOS)
 
+#if BUILDFLAG(IS_ANDROID)
+  // Denotes the time at which Chrome clients in the Extended Variations Safe
+  // Mode experiment's enabled group start watching for browser crashes.
+  base::TimeTicks extended_monitoring_stage_start_time_;
+#endif
+
   // Indicates whether the CleanExitBeacon has been initialized.
   bool initialized_ = false;
 

components/metrics/clean_exit_beacon_unittest.cc

@@ -822,4 +822,67 @@ TEST_P(BeaconFileAndPlatformBeaconConsistencyTest, BeaconConsistency) {
 }
 #endif  // BUILDFLAG(IS_IOS)
 
+#if BUILDFLAG(IS_ANDROID)
+TEST_F(CleanExitBeaconTest, EnabledGroupEmitsStageDurationMetric) {
+  // Force the client into the Extended Variations Safe Mode experiment's
+  // enabled group.
+  SetUpExtendedSafeModeExperiment(variations::kEnabledGroup);
+
+  // Create and initialize the CleanExitBeacon.
+  TestCleanExitBeacon clean_exit_beacon(&prefs_);
+
+  // Simulate Chrome starting to watch for browser crashes for enabled-group
+  // clients.
+  clean_exit_beacon.WriteBeaconValue(/*exited_cleanly=*/false,
+                                     /*is_extended_safe_mode=*/true);
+  // Verify that the metric has not yet been emitted.
+  histogram_tester_.ExpectTotalCount(
+      "UMA.CleanExitBeacon.ExtendedMonitoringStageDuration", 0);
+
+  // Simulate Chrome continuing to watch for crashes once the app enters the
+  // foreground.
+  clean_exit_beacon.WriteBeaconValue(/*exited_cleanly=*/false,
+                                     /*is_extended_safe_mode=*/false);
+  // Verify that the metric was emitted.
+  histogram_tester_.ExpectTotalCount(
+      "UMA.CleanExitBeacon.ExtendedMonitoringStageDuration", 1);
+
+  // Make the same call. Note that these two identical, consecutive calls to
+  // WriteBeaconValue() shouldn't actually happen, but this is done for the
+  // purpose of the test.
+  clean_exit_beacon.WriteBeaconValue(/*exited_cleanly=*/false,
+                                     /*is_extended_safe_mode=*/false);
+  // Verify that the metric was not emitted again.
+  histogram_tester_.ExpectTotalCount(
+      "UMA.CleanExitBeacon.ExtendedMonitoringStageDuration", 1);
+}
+
+TEST_F(CleanExitBeaconTest, ControlGroupDoesNotEmitStageDurationMetric) {
+  // Force the client into the Extended Variations Safe Mode experiment's
+  // control group.
+  SetUpExtendedSafeModeExperiment(variations::kControlGroup);
+
+  // Create and initialize the CleanExitBeacon.
+  TestCleanExitBeacon clean_exit_beacon(&prefs_);
+
+  // Simulate Chrome starting to watch for browser crashes for control-group
+  // clients once the app enters the foreground.
+  clean_exit_beacon.WriteBeaconValue(/*exited_cleanly=*/false,
+                                     /*is_extended_safe_mode=*/false);
+  // Verify that the metric was not emitted.
+  histogram_tester_.ExpectTotalCount(
+      "UMA.CleanExitBeacon.ExtendedMonitoringStageDuration", 0);
+
+  // Make the same call. Note that these two identical, consecutive calls to
+  // WriteBeaconValue() shouldn't actually happen, but this is done for the
+  // purpose of the test.
+  clean_exit_beacon.WriteBeaconValue(/*exited_cleanly=*/false,
+                                     /*is_extended_safe_mode=*/false);
+  // Verify that the metric was not emitted.
+  histogram_tester_.ExpectTotalCount(
+      "UMA.CleanExitBeacon.ExtendedMonitoringStageDuration", 0);
+}
+
+#endif  //  BUILDFLAG(IS_ANDROID)
+
 }  // namespace metrics

tools/metrics/histograms/metadata/uma/histograms.xml

@@ -114,6 +114,20 @@ chromium-metrics-reviews@google.com.
   </summary>
 </histogram>
 
+<histogram name="UMA.CleanExitBeacon.ExtendedMonitoringStageDuration"
+    units="ms" expires_after="2022-11-01">
+  <owner>ssid@chromium.org</owner>
+  <owner>wnwen@chromium.org</owner>
+  <summary>
+    The amount of time in ms between the extended and status quo browser crash
+    monitoring stages. The extended monitoring stage may begin in
+    MaybeExtendVariationsSafeMode(), and the status quo stage begins in
+    MetricsService::OnAppEnterForeground(). Emitted when the status quo
+    monitoring stage begins. Recorded by Extended Variations Safe Mode
+    enabled-group clients on Android Chrome.
+  </summary>
+</histogram>
+
 <histogram name="UMA.CleanExitBeacon.MonitoringStage"
     enum="BeaconMonitoringStage" expires_after="2022-10-04">
   <owner>caitlinfischer@google.com</owner>