1 // Copyright 2020 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "components/metrics/date_changed_helper.h"
6
7 #include "base/time/time.h"
8 #include "components/prefs/pref_registry_simple.h"
9 #include "components/prefs/pref_service.h"
10
11 namespace metrics {
12
13 namespace {
14
GetCurrentDate(base::Time now)15 base::Time GetCurrentDate(base::Time now) {
16 // Use local midnight to ensure reporting is for calendar days, not UTC, and
17 // avoid storing extra information about when this was called.
18 return now.LocalMidnight();
19 }
20
UpdateStoredDate(PrefService * prefs,const char * pref_name,base::Time now)21 void UpdateStoredDate(PrefService* prefs,
22 const char* pref_name,
23 base::Time now) {
24 prefs->SetTime(pref_name, GetCurrentDate(now));
25 }
26
IsStoredDateToday(PrefService * prefs,const char * pref_name,base::Time now)27 bool IsStoredDateToday(PrefService* prefs,
28 const char* pref_name,
29 base::Time now) {
30 base::Time stored_date = prefs->GetTime(pref_name);
31 if (stored_date.is_null()) {
32 // Consider date unchanged if pref has never been set.
33 UpdateStoredDate(prefs, pref_name, GetCurrentDate(now));
34 return true;
35 }
36 // Ignore small changes in midnight such as time zone changes.
37 return std::abs((stored_date - GetCurrentDate(now)).InHours()) < 12;
38 }
39
40 } // namespace
41
42 namespace date_changed_helper {
43
HasDateChangedSinceLastCall(PrefService * prefs,const char * pref_name)44 bool HasDateChangedSinceLastCall(PrefService* prefs, const char* pref_name) {
45 DCHECK(prefs);
46 DCHECK(pref_name);
47 base::Time now = base::Time::Now();
48 if (IsStoredDateToday(prefs, pref_name, now))
49 return false;
50 UpdateStoredDate(prefs, pref_name, now);
51 return true;
52 }
53
RegisterPref(PrefRegistrySimple * registry,const char * pref_name)54 void RegisterPref(PrefRegistrySimple* registry, const char* pref_name) {
55 registry->RegisterTimePref(pref_name, base::Time());
56 }
57
58 } // namespace date_changed_helper
59
60 } // namespace metrics
61