Multi-strategy based tracking.

chrome/browser/prefs/tracked/tracked_atomic_preference.cc

+// 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 "chrome/browser/prefs/tracked/tracked_atomic_preference.h"
+
+#include "base/values.h"
+
+TrackedAtomicPreference::TrackedAtomicPreference(
+    const std::string& pref_path,
+    size_t reporting_id,
+    size_t reporting_ids_count,
+    PrefHashFilter::EnforcementLevel enforcement_level)
+    : pref_path_(pref_path),
+      helper_(pref_path, reporting_id, reporting_ids_count, enforcement_level) {
+}
+
+void TrackedAtomicPreference::OnValueChanged(
+    const base::Value* value,
+    PrefHashStore* pref_hash_store) const {
+  pref_hash_store->StoreHash(pref_path_, value);

[erikwright (departed), 2014/01/21 18:44:45]

pref_hash_store.h

[gab, 2014/01/21 20:51:42]

Done.

+}
+
+void TrackedAtomicPreference::EnforceAndReport(
+    PrefHashStore* pref_hash_store,
+    base::DictionaryValue* pref_store_contents) const {
+  const base::Value* value = NULL;
+  pref_store_contents->Get(pref_path_, &value);
+  PrefHashStore::ValueState value_state =
+      pref_hash_store->CheckValue(pref_path_, value);
+
+  helper_.ReportValidationResult(value_state);
+
+  TrackedPreferenceHelper::ResetAction reset_action =
+      helper_.GetAction(value_state);
+  helper_.ReportAction(reset_action);
+
+  if (reset_action == TrackedPreferenceHelper::DO_RESET)
+    pref_store_contents->RemovePath(pref_path_, NULL);
+
+  if (value_state != PrefHashStore::UNCHANGED) {
+    // Store the hash for the new value (whether it was reset or not).
+    const base::Value* new_value = NULL;
+    pref_store_contents->Get(pref_path_, &new_value);
+    pref_hash_store->StoreHash(pref_path_, new_value);
+  }
+}