1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_METRICS_USER_METRICS_H_
6#define BASE_METRICS_USER_METRICS_H_
7
8#include <string>
9
10#include "base/base_export.h"
11#include "base/callback.h"
12#include "base/metrics/user_metrics_action.h"
13
14namespace base {
15
16// This module provides some helper functions for logging actions tracked by
17// the user metrics system.
18
19// Record that the user performed an action.
20// This method *must* be called from the main thread.
21//
22// "Action" here means a user-generated event:
23//   good: "Reload", "CloseTab", and "IMEInvoked"
24//   not good: "SSLDialogShown", "PageLoaded", "DiskFull"
25// We use this to gather anonymized information about how users are
26// interacting with the browser.
27// WARNING: In calls to this function, UserMetricsAction and a
28// string literal parameter must be on the same line, e.g.
29//   RecordAction(UserMetricsAction("my extremely long action name"));
30// This ensures that our processing scripts can associate this action's hash
31// with its metric name. Therefore, it will be possible to retrieve the metric
32// name from the hash later on.
33//
34// Once a new recorded action is added, run
35//   tools/metrics/actions/extract_actions.py
36// to add the metric to actions.xml, then update the <owner>s and <description>
37// sections. Make sure to include the actions.xml file when you upload your code
38// for review!
39//
40// For more complicated situations (like when there are many different
41// possible actions), see RecordComputedAction.
42BASE_EXPORT void RecordAction(const UserMetricsAction& action);
43
44// This function has identical input and behavior to RecordAction, but is
45// not automatically found by the action-processing scripts.  It can be used
46// when it's a pain to enumerate all possible actions, but if you use this
47// you need to also update the rules for extracting known actions in
48// tools/metrics/actions/extract_actions.py.
49BASE_EXPORT void RecordComputedAction(const std::string& action);
50
51// Called with the action string.
52typedef base::Callback<void(const std::string&)> ActionCallback;
53
54// Add/remove action callbacks (see above).
55BASE_EXPORT void AddActionCallback(const ActionCallback& callback);
56BASE_EXPORT void RemoveActionCallback(const ActionCallback& callback);
57
58}  // namespace base
59
60#endif  // BASE_METRICS_USER_METRICS_H_
61