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 155be5b79cd3413135de7152d64bb614cb8dd6b9..c6a0adff324c92f57a0100d3e5ce7606f689c1d9 100644
--- a/ash/metrics/task_switch_metrics_recorder_unittest.cc
+++ b/ash/metrics/task_switch_metrics_recorder_unittest.cc
@@ -77,4 +77,19 @@ 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