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

ash/metrics/task_switch_metrics_recorder.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 "ash/metrics/task_switch_time_tracker.h"
+#include "ui/aura/window.h"
+#include "ui/wm/public/window_types.h"
 
 namespace ash {
 
 namespace {
 
+const char kScreenHistogramName[] =
+    "Ash.Screen.TimeBetweenNavigateToTaskSwitches";

[tdanderson, 2015/05/26 21:13:52]

don't forget to update histograms.xml

[bruthig, 2015/06/03 21:59:31]

Done.

+
 const char kShelfHistogramName[] =
     "Ash.Shelf.TimeBetweenNavigateToTaskSwitches";
 
 const char kTabStripHistogramName[] =
     "Ash.Tab.TimeBetweenSwitchToExistingTabUserActions";
 
 const char kAcceleratorWindowCycleHistogramName[] =
     "Ash.WindowCycleController.TimeBetweenTaskSwitches";
 
 const char kAppListHistogramName[] = "Ash.AppList.TimeBetweenTaskSwitches";
 
 const char kOverviewModeHistogramName[] =
     "Ash.WindowSelector.TimeBetweenActiveWindowChanges";
 
 // Returns the histogram name for the given |task_switch_source|.
 const char* GetHistogramName(
     TaskSwitchMetricsRecorder::TaskSwitchSource task_switch_source) {
   switch (task_switch_source) {
     case TaskSwitchMetricsRecorder::kAppList:
       return kAppListHistogramName;
     case TaskSwitchMetricsRecorder::kOverviewMode:
       return kOverviewModeHistogramName;
+    case TaskSwitchMetricsRecorder::kScreen:
+      return kScreenHistogramName;
     case TaskSwitchMetricsRecorder::kShelf:
       return kShelfHistogramName;
     case TaskSwitchMetricsRecorder::kTabStrip:
       return kTabStripHistogramName;
     case TaskSwitchMetricsRecorder::kWindowCycleController:
       return kAcceleratorWindowCycleHistogramName;
   }
   NOTREACHED();
   return nullptr;
 }
@@ skipping 12 matching lines @@
       FindTaskSwitchTimeTracker(task_switch_source);
   if (!task_switch_time_tracker)
     AddTaskSwitchTimeTracker(task_switch_source);
 
   task_switch_time_tracker = FindTaskSwitchTimeTracker(task_switch_source);
   CHECK(task_switch_time_tracker);
 
   task_switch_time_tracker->OnTaskSwitch();
 }
 
+bool TaskSwitchMetricsRecorder::IsATaskWindow(aura::Window* window) const {
+  return window && (window->type() == ui::wm::WINDOW_TYPE_NORMAL ||

[tdanderson, 2015/05/26 21:13:52]

It might be nice to define this as a static utility function somewhere in
ash/wm. Six other places in the code perform this same check, and they could
instead call into the utility function:

* CanHandleWindowSnapOrDock() in accelerator_controller.cc

* RootWindowController::GetWindowForFullscreenMode()

* DragWindowResizer::ShouldAllowMouseWarp()

* WindowSelector::IsSelectable()

...and be sure to dust off your notes from logic class because you'll be needing
DeMorgan's law for the last two:

* WindowWatcher::OnWindowAdded()

* DefaultState::ProcessWorkspaceEvents()

The benefit here is not just saving ~6 lines of code, but in naming the utility
function to describe a unique characteristic of windows which are normal or
panel types. One suggestion is IsWindowUserPositionable() but perhaps that isn't
the best. Whatever name you pick can be used in place of "task window".

[bruthig, 2015/06/03 21:59:31]

Done.

+                    window->type() == ui::wm::WINDOW_TYPE_PANEL);
+}
+
 TaskSwitchTimeTracker* TaskSwitchMetricsRecorder::FindTaskSwitchTimeTracker(
     TaskSwitchSource task_switch_source) {
   return histogram_map_.get(task_switch_source);
 }
 
 void TaskSwitchMetricsRecorder::AddTaskSwitchTimeTracker(
     TaskSwitchSource task_switch_source) {
   CHECK(histogram_map_.find(task_switch_source) == histogram_map_.end());
 
   const char* histogram_name = GetHistogramName(task_switch_source);
   DCHECK(histogram_name);
 
   histogram_map_.add(
       task_switch_source,
       make_scoped_ptr(new TaskSwitchTimeTracker(histogram_name)));
 }
 
 }  // namespace ash