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// Copyright 2015 The Chromium Authors
// 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_METRICS_RECORDER_H_
#define ASH_METRICS_TASK_SWITCH_METRICS_RECORDER_H_
#include <memory>
#include <string>
#include <unordered_map>
#include "ash/ash_export.h"
#include "ash/metrics/task_switch_source.h"
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:
TaskSwitchMetricsRecorder();
TaskSwitchMetricsRecorder(const TaskSwitchMetricsRecorder&) = delete;
TaskSwitchMetricsRecorder& operator=(const TaskSwitchMetricsRecorder&) =
delete;
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.
//
// A "navigate to" operation is defined by a task switch where the specific
// task that becomes active is user-predictable (e.g., Alt+Tab accelerator,
// launching a new window via the shelf, etc). Contrast to a "navigate away"
// operation which is defined as a user interaction that navigates away from a
// specified task and the next task that becomes active is likely not
// user-predictable (e.g., closing or minimizing a window, closing a tab,
// etc).
//
// Will add an entry to |histogram_map_| when called for the first time for
// each |task_switch_source| value.
void OnTaskSwitch(TaskSwitchSource task_switch_source);
private:
// Internal implementation of OnTaskSwitch(TaskSwitchSource) that will accept
// the TaskSwitchSource::ANY value.
void OnTaskSwitchInternal(TaskSwitchSource task_switch_source);
// Returns the TaskSwitchTimeTracker associated with the specified
// |task_switch_source|. May return nullptr if mapping does not exist yet.
TaskSwitchTimeTracker* FindTaskSwitchTimeTracker(
TaskSwitchSource task_switch_source);
// Adds a TaskSwitchTimeTracker to |histogram_map_| for the specified
// |task_switch_source|. Behavior is undefined if a TaskSwitchTimeTracker
// |histogram_map_| already has an entry for |task_switch_source|.
void AddTaskSwitchTimeTracker(TaskSwitchSource task_switch_source);
// Tracks TaskSwitchSource to TaskSwitchTimeTracker mappings. The
// |histogram_map_| is populated on demand the first time a
// TaskSwitchTimeTracker is needed for a given source.
std::unordered_map<int, std::unique_ptr<TaskSwitchTimeTracker>>
histogram_map_;
};
} // namespace ash
#endif // ASH_METRICS_TASK_SWITCH_METRICS_RECORDER_H_
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