Added metrics to track the time between task switches done via Alt+Tab and Alt+Shift+Tab.

TEST=TaskSwitchMetricsRecorderTest.VerifyTaskSwitchesForWindowCycleControllerAreRecorded

BUG=478946

Review URL: https://codereview.chromium.org/1126333005

Cr-Commit-Position: refs/heads/master@{#330099}

7 files changed, 72 insertions, 3 deletions

diff --git a/ash/metrics/task_switch_metrics_recorder.cc b/ash/metrics/task_switch_metrics_recorder.cc
index 667c7e4..a22602c 100644
--- a/ash/metrics/task_switch_metrics_recorder.cc
+++ b/ash/metrics/task_switch_metrics_recorder.cc
@@ -13,12 +13,17 @@ namespace {
 const char kShelfHistogramName[] =
     "Ash.Shelf.TimeBetweenNavigateToTaskSwitches";
 
+const char kAcceleratorWindowCycleHistogramName[] =
+    "Ash.WindowCycleController.TimeBetweenTaskSwitches";
+
 // Returns the histogram name for the given |task_switch_source|.
 const char* GetHistogramName(
     TaskSwitchMetricsRecorder::TaskSwitchSource task_switch_source) {
   switch (task_switch_source) {
     case TaskSwitchMetricsRecorder::kShelf:
       return kShelfHistogramName;
+    case TaskSwitchMetricsRecorder::kWindowCycleController:
+      return kAcceleratorWindowCycleHistogramName;
   }
   NOTREACHED();
   return nullptr;
diff --git a/ash/metrics/task_switch_metrics_recorder.h b/ash/metrics/task_switch_metrics_recorder.h
index 87a7760..c0827cc 100644
--- a/ash/metrics/task_switch_metrics_recorder.h
+++ b/ash/metrics/task_switch_metrics_recorder.h
@@ -23,7 +23,9 @@ class ASH_EXPORT TaskSwitchMetricsRecorder {
   // a task switch. Note this is not necessarily comprehensive of all sources.
   enum TaskSwitchSource {
     // All task switches caused by shelf buttons, not including sub-menus.
-    kShelf
+    kShelf,
+    // Task switches caused by the WindowCycleController (ie Alt+Tab).
+    kWindowCycleController
   };
 
   TaskSwitchMetricsRecorder();
diff --git a/ash/metrics/task_switch_metrics_recorder_unittest.cc b/ash/metrics/task_switch_metrics_recorder_unittest.cc
index 155be5b..ca3078e 100644
--- a/ash/metrics/task_switch_metrics_recorder_unittest.cc
+++ b/ash/metrics/task_switch_metrics_recorder_unittest.cc
@@ -62,6 +62,21 @@ void TaskSwitchMetricsRecorderTest::TearDown() {
 
 }  // namespace
 
+// 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);
+
+  OnTaskSwitch(TaskSwitchMetricsRecorder::kWindowCycleController);
+  histogram_tester_->ExpectTotalCount(kHistogramName, 2);
+}
+
 // Verifies that the TaskSwitchMetricsRecorder::kShelf source adds data to the
 // Ash.Shelf.TimeBetweenNavigateToTaskSwitches histogram.
 TEST_F(TaskSwitchMetricsRecorderTest,
diff --git a/ash/metrics/user_metrics_recorder.h b/ash/metrics/user_metrics_recorder.h
index 956bb40..7bb6f9d 100644
--- a/ash/metrics/user_metrics_recorder.h
+++ b/ash/metrics/user_metrics_recorder.h
@@ -149,6 +149,10 @@ class ASH_EXPORT UserMetricsRecorder {
   // Records an Ash owned user action.
   void RecordUserMetricsAction(ash::UserMetricsAction action);
 
+  TaskSwitchMetricsRecorder& task_switch_metrics_recorder() {
+    return task_switch_metrics_recorder_;
+  }
+
  private:
   friend class test::UserMetricsRecorderTestAPI;
 
diff --git a/ash/wm/window_cycle_controller.cc b/ash/wm/window_cycle_controller.cc
index 42f866e..d2366c3 100644
--- a/ash/wm/window_cycle_controller.cc
+++ b/ash/wm/window_cycle_controller.cc
@@ -4,11 +4,13 @@
 
 #include "ash/wm/window_cycle_controller.h"
 
+#include "ash/metrics/user_metrics_recorder.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/window_cycle_list.h"
 #include "base/metrics/histogram.h"
+#include "ui/aura/window.h"
 #include "ui/events/event.h"
 #include "ui/events/event_handler.h"
 
@@ -16,6 +18,12 @@ namespace ash {
 
 namespace {
 
+// Returns the most recently active window from the |window_list| or nullptr
+// if the list is empty.
+aura::Window* GetActiveWindow(const MruWindowTracker::WindowList& window_list) {
+  return window_list.empty() ? nullptr : window_list[0];
+}
+
 // Filter to watch for the termination of a keyboard gesture to cycle through
 // multiple windows.
 class WindowCycleEventFilter : public ui::EventHandler {
@@ -77,8 +85,12 @@ void WindowCycleController::HandleCycleWindow(Direction direction) {
 }
 
 void WindowCycleController::StartCycling() {
-  window_cycle_list_.reset(new WindowCycleList(ash::Shell::GetInstance()->
-      mru_window_tracker()->BuildMruWindowList()));
+  MruWindowTracker::WindowList window_list =
+      Shell::GetInstance()->mru_window_tracker()->BuildMruWindowList();
+
+  active_window_before_window_cycle_ = GetActiveWindow(window_list);
+
+  window_cycle_list_.reset(new WindowCycleList(window_list));
   event_handler_.reset(new WindowCycleEventFilter());
   cycle_start_time_ = base::Time::Now();
   Shell::GetInstance()->metrics()->RecordUserMetricsAction(UMA_WINDOW_CYCLE);
@@ -94,10 +106,23 @@ void WindowCycleController::Step(Direction direction) {
 
 void WindowCycleController::StopCycling() {
   window_cycle_list_.reset();
+
+  aura::Window* active_window_after_window_cycle = GetActiveWindow(
+      Shell::GetInstance()->mru_window_tracker()->BuildMruWindowList());
+
   // Remove our key event filter.
   event_handler_.reset();
   UMA_HISTOGRAM_MEDIUM_TIMES("Ash.WindowCycleController.CycleTime",
                              base::Time::Now() - cycle_start_time_);
+
+  if (active_window_after_window_cycle != nullptr &&
+      active_window_before_window_cycle_ != active_window_after_window_cycle) {
+    Shell::GetInstance()
+        ->metrics()
+        ->task_switch_metrics_recorder()
+        .OnTaskSwitch(TaskSwitchMetricsRecorder::kWindowCycleController);
+  }
+  active_window_before_window_cycle_ = nullptr;
 }
 
 }  // namespace ash
diff --git a/ash/wm/window_cycle_controller.h b/ash/wm/window_cycle_controller.h
index 4120bc0..8cfd2a5 100644
--- a/ash/wm/window_cycle_controller.h
+++ b/ash/wm/window_cycle_controller.h
@@ -14,6 +14,10 @@ namespace ui {
 class EventHandler;
 }
 
+namespace aura {
+class Window;
+}  // namespace aura
+
 namespace ash {
 
 class WindowCycleList;
@@ -63,6 +67,10 @@ class ASH_EXPORT WindowCycleController {
 
   scoped_ptr<WindowCycleList> window_cycle_list_;
 
+  // Tracks what Window was active when starting to cycle and used to determine
+  // if the active Window changed in when ending cycling.
+  aura::Window* active_window_before_window_cycle_ = nullptr;
+
   // Event handler to watch for release of alt key.
   scoped_ptr<ui::EventHandler> event_handler_;
 
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 4817881..9ced647 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -916,6 +916,16 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Ash.WindowCycleController.TimeBetweenTaskSwitches"
+    units="seconds">
+  <owner>tdanderson@google.com</owner>
+  <owner>bruthig@google.com</owner>
+  <summary>
+    The number of seconds between task switches triggered by the next window and
+    previous window accelerator keys (ie Alt+Tab, Alt+Shift+Tab).
+  </summary>
+</histogram>
+
 <histogram name="Ash.WindowSelector.ArrowKeyPresses">
   <owner>flackr@chromium.org</owner>
   <owner>tdanderson@chromium.org</owner>