Added UMA statistics for changing the active window via click or touch events.

ash/metrics/task_switch_metrics_recorder_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/metrics/task_switch_metrics_recorder.h"
 
 #include "base/test/histogram_tester.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace ash {
@@ skipping 44 matching lines @@
 
 void TaskSwitchMetricsRecorderTest::TearDown() {
   testing::Test::TearDown();
 
   histogram_tester_.reset();
   task_switch_metrics_recorder_.reset();
 }
 
 }  // namespace
 
+// Verifies that the TaskSwitchMetricsRecorder::kDesktop source adds data to the
+// Ash.Desktop.TimeBetweenNavigateToTaskSwitches histogram.
+TEST_F(TaskSwitchMetricsRecorderTest, VerifyTaskSwitchesForDesktopAreRecorded) {
+  const std::string kHistogramName =
+      "Ash.Desktop.TimeBetweenNavigateToTaskSwitches";
+
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kDesktop);
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kDesktop);
+  histogram_tester_->ExpectTotalCount(kHistogramName, 1);
+
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kDesktop);
+  histogram_tester_->ExpectTotalCount(kHistogramName, 2);
+}
+
 // Verifies that the TaskSwitchMetricsRecorder::kWindowCycleController source
 // adds data to the Ash.WindowCycleController.TimeBetweenTaskSwitches histogram.
 TEST_F(TaskSwitchMetricsRecorderTest,
        VerifyTaskSwitchesForWindowCycleControllerAreRecorded) {
   const std::string kHistogramName =
       "Ash.WindowCycleController.TimeBetweenTaskSwitches";
 
   OnTaskSwitch(TaskSwitchMetricsRecorder::kWindowCycleController);
   OnTaskSwitch(TaskSwitchMetricsRecorder::kWindowCycleController);
   histogram_tester_->ExpectTotalCount(kHistogramName, 1);
@@ skipping 55 matching lines @@
 
   OnTaskSwitch(TaskSwitchMetricsRecorder::kAppList);
   OnTaskSwitch(TaskSwitchMetricsRecorder::kAppList);
   histogram_tester_->ExpectTotalCount(kHistogramName, 1);
 
   OnTaskSwitch(TaskSwitchMetricsRecorder::kAppList);
   histogram_tester_->ExpectTotalCount(kHistogramName, 2);
 }
 
 }  // namespace ash