1 files changed, 98 insertions, 0 deletions
diff --git a/components/metrics/cloned_install_detector.cc b/components/metrics/cloned_install_detector.cc
new file mode 100644
index 0000000..b93e6e6
--- /dev/null
+++ b/components/metrics/cloned_install_detector.cc
@@ -0,0 +1,98 @@
+// Copyright 2014 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/metrics/cloned_install_detector.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/metrics/histogram.h"
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/pref_service.h"
+#include "base/single_thread_task_runner.h"
+#include "base/task_runner_util.h"
+#include "components/metrics/cloned_install_detector.h"
+#include "components/metrics/machine_id_provider.h"
+#include "components/metrics/metrics_hashes.h"
+#include "components/metrics/metrics_pref_names.h"
+
+namespace metrics {
+
+namespace {
+
+uint32 HashRawId(const std::string& value) {
+  uint64 hash = metrics::HashMetricName(value);
+
+  // Only use 24 bits from the 64-bit hash.
+  return hash & ((1 << 24) - 1);
+}
+
+// State of the generated machine id in relation to the previously stored value.
+// Note: UMA histogram enum - don't re-order or remove entries
+enum MachineIdState {
+  ID_GENERATION_FAILED,
+  ID_NO_STORED_VALUE,
+  ID_CHANGED,
+  ID_UNCHANGED,
+  ID_ENUM_SIZE
+};
+
+// Logs the state of generating a machine id and comparing it to a stored value.
+void LogMachineIdState(MachineIdState state) {
+  UMA_HISTOGRAM_ENUMERATION("UMA.MachineIdState", state, ID_ENUM_SIZE);
+}
+
+}  // namespace
+
+ClonedInstallDetector::ClonedInstallDetector(MachineIdProvider* raw_id_provider)
+    : raw_id_provider_(raw_id_provider), weak_ptr_factory_(this) {
+}
+
+ClonedInstallDetector::~ClonedInstallDetector() {
+}
+
+void ClonedInstallDetector::CheckForClonedInstall(
+    PrefService* local_state,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
+  base::PostTaskAndReplyWithResult(
+      task_runner.get(),
+      FROM_HERE,
+      base::Bind(&metrics::MachineIdProvider::GetMachineId, raw_id_provider_),
+      base::Bind(&metrics::ClonedInstallDetector::SaveMachineId,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 local_state));
+}
+
+void ClonedInstallDetector::SaveMachineId(PrefService* local_state,
+                                          std::string raw_id) {
+  if (raw_id.empty()) {
+    LogMachineIdState(ID_GENERATION_FAILED);
+    local_state->ClearPref(prefs::kMetricsMachineId);
+    return;
+  }
+
+  int hashed_id = HashRawId(raw_id);
+
+  MachineIdState id_state = ID_NO_STORED_VALUE;
+  if (local_state->HasPrefPath(prefs::kMetricsMachineId)) {
+    if (local_state->GetInteger(prefs::kMetricsMachineId) != hashed_id) {
+      id_state = ID_CHANGED;
+      // TODO(jwd): Use a callback to set the reset pref. That way
+      // ClonedInstallDetector doesn't need to know about this pref.
+      local_state->SetBoolean(prefs::kMetricsResetIds, true);
+    } else {
+      id_state = ID_UNCHANGED;
+    }
+  }
+
+  LogMachineIdState(id_state);
+
+  local_state->SetInteger(prefs::kMetricsMachineId, hashed_id);
+}
+
+// static
+void ClonedInstallDetector::RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterIntegerPref(prefs::kMetricsMachineId, 0);
+}
+
+}  // namespace metrics