Record time between switching the active window from Ash overview mode

ash/metrics/task_switch_metrics_recorder_unittest.cc

Index: ash/metrics/task_switch_metrics_recorder_unittest.cc
diff --git a/ash/metrics/task_switch_metrics_recorder_unittest.cc b/ash/metrics/task_switch_metrics_recorder_unittest.cc
index ca3078e3394086e02d4b464fd936265ca1f8802e..f1971c4c5516ae619bc2a3138cf53d5c2b28ce87 100644
--- a/ash/metrics/task_switch_metrics_recorder_unittest.cc
+++ b/ash/metrics/task_switch_metrics_recorder_unittest.cc
@@ -92,4 +92,19 @@ TEST_F(TaskSwitchMetricsRecorderTest,
   histogram_tester_->ExpectTotalCount(kHistogramName, 2);
 }
 
+// Verifies that the TaskSwitchMetricsRecorder::kOverviewMode source adds data
+// to the Ash.WindowSelector.TimeBetweenActiveWindowChanges histogram.
+TEST_F(TaskSwitchMetricsRecorderTest,
+       VerifyTaskSwitchesFromOverviewModeAreRecorded) {
+  const std::string kHistogramName =
+      "Ash.WindowSelector.TimeBetweenActiveWindowChanges";
+
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kOverviewMode);
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kOverviewMode);
+  histogram_tester_->ExpectTotalCount(kHistogramName, 1);
+
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kOverviewMode);
+  histogram_tester_->ExpectTotalCount(kHistogramName, 2);
+}
+
 }  // namespace ash