Adds WmShell::RecordTaskSwitchMetric()

ash/metrics/task_switch_metrics_recorder.h

 // 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.
 
 #ifndef ASH_METRICS_TASK_SWITCH_METRIC_RECORDER_H_
 #define ASH_METRICS_TASK_SWITCH_METRIC_RECORDER_H_
 
 #include <memory>
 #include <string>
 
 #include "ash/ash_export.h"
+#include "ash/common/metrics/task_switch_source.h"
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/macros.h"
 
-namespace aura {
-class Window;
-}  // namespace aura
-
 namespace ash {
 
 class TaskSwitchTimeTracker;
 
 // The TaskSwitchMetricsRecorder class records UMA metrics related to task
 // switching. The main purpose of the TaskSwitchMetricsRecorder is to track time
 // deltas between task switches and record histograms of the deltas.
 class ASH_EXPORT TaskSwitchMetricsRecorder {
  public:
-  // Enumeration of the different user interfaces that could be the source of
-  // a task switch. Note this is not necessarily comprehensive of all sources.
-  enum TaskSwitchSource {
-    // Task switches caused by any two sources in this enum. NOTE: This value
-    // should NOT be used outside of this class.
-    ANY,
-    // Task switches from selecting items in the app list.
-    APP_LIST,
-    // Task switches caused by the user activating a task window by clicking or
-    // tapping on it.
-    DESKTOP,
-    // Task switches caused by selecting a window from overview mode which is
-    // different from the previously-active window.
-    OVERVIEW_MODE,
-    // All task switches caused by shelf buttons, not including sub-menus.
-    SHELF,
-    // All task switches caused by the tab strip.
-    TAB_STRIP,
-    // Task switches caused by the WindowCycleController (ie Alt+Tab).
-    WINDOW_CYCLE_CONTROLLER
-  };
-
   TaskSwitchMetricsRecorder();
   virtual ~TaskSwitchMetricsRecorder();
 
   // Notifies |this| that a "navigate to" task switch has occurred from the
   // specified |task_switch_source|. The metrics associated with
   // TaskSwitchSource::ANY source will be updated as well.
   //
   // NOTE: A |task_switch_source| value of TaskSwitchSource::ANY should not be
   // used and behavior is undefined if it is.
   //
@@ skipping 29 matching lines @@
   // TaskSwitchTimeTracker is needed for a given source.
   base::ScopedPtrHashMap<int, std::unique_ptr<TaskSwitchTimeTracker>>
       histogram_map_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskSwitchMetricsRecorder);
 };
 
 }  // namespace ash
 
 #endif  // ASH_METRICS_TASK_SWITCH_METRIC_RECORDER_H_