Add module for counting date-last-roll-call and persisting those counts

components/update_client/persisted_data.cc

Index: components/update_client/persisted_data.cc
diff --git a/components/update_client/persisted_data.cc b/components/update_client/persisted_data.cc
new file mode 100644
index 0000000000000000000000000000000000000000..95598d9ec0985f66e674704577e188b56dc8c080
--- /dev/null
+++ b/components/update_client/persisted_data.cc
@@ -0,0 +1,60 @@
+// Copyright 2016 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 "components/update_client/persisted_data.h"
+
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "base/values.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+#include "components/prefs/scoped_user_pref_update.h"
+
+const char kPersistedDataPreference[] = "updateclientdata";
+const int kDateLastRollCallUnknown = -2;
+
+namespace update_client {
+
+PersistedData::PersistedData(PrefService* pref_service)
+    : pref_service_(pref_service) {}
+
+PersistedData::~PersistedData() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+int PersistedData::GetDateLastRollCall(const std::string& id) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!pref_service_)
+    return kDateLastRollCallUnknown;
+  int dlrc = kDateLastRollCallUnknown;
+  const base::DictionaryValue* dict =
+      pref_service_->GetDictionary(kPersistedDataPreference);
+  // We assume ids do not contain '.' characters.
+  DCHECK(std::string::npos == id.find('.'));

[Bernhard Bauer, 2016/04/08 21:54:07]

Nit: Use DCHECK_EQ for nicer error messages in case of a failure (keeping the
expected value first).

[waffles, 2016/04/08 22:00:49]

Done.

+  if (!dict->GetInteger("apps." + id + ".dlrc", &dlrc))
+    return kDateLastRollCallUnknown;
+  return dlrc;
+}
+
+void PersistedData::SetDateLastRollCall(const std::vector<std::string>& ids,
+                                        int datenum) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!pref_service_ || datenum < 0)
+    return;
+  DictionaryPrefUpdate update(pref_service_, kPersistedDataPreference);
+  for (auto id : ids) {
+    // We assume ids do not contain '.' characters.
+    DCHECK(std::string::npos == id.find('.'));
+    update->SetInteger("apps." + id + ".dlrc", datenum);
+  }
+}
+
+void PersistedData::RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterDictionaryPref(kPersistedDataPreference);
+}
+
+}  // namespace update_client