Added Ash.TimeBetweenTaskSwitches to record time deltas between all recorded task switches.

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 90a0db1fe07d08d86bc45db92d135d167d433e16..be0eafc46d297087a80d952066d48f7f6b97dcb8 100644
--- a/ash/metrics/task_switch_metrics_recorder_unittest.cc
+++ b/ash/metrics/task_switch_metrics_recorder_unittest.cc
@@ -62,6 +62,17 @@ void TaskSwitchMetricsRecorderTest::TearDown() {
 
 }  // namespace
 
+// Verifies that task switches from a non kAny source also add data to the
+// Ash.TimeBetweenTaskSwitches histogram.
+TEST_F(TaskSwitchMetricsRecorderTest,
+       VerifyTaskSwitchesRecordInAllTaskSwitchHistogram) {
+  const std::string kHistogramName = "Ash.TimeBetweenTaskSwitches";
+
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kShelf);
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kShelf);
+  histogram_tester_->ExpectTotalCount(kHistogramName, 1);
+}
+
 // Verifies that the TaskSwitchMetricsRecorder::kWindowCycleController source
 // adds data to the Ash.WindowCycleController.TimeBetweenTaskSwitches histogram.
 TEST_F(TaskSwitchMetricsRecorderTest,