Multi-strategy based tracking.

chrome/browser/prefs/tracked_atomic_preference.h

Index: chrome/browser/prefs/tracked_atomic_preference.h
diff --git a/chrome/browser/prefs/tracked_atomic_preference.h b/chrome/browser/prefs/tracked_atomic_preference.h
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+++ b/chrome/browser/prefs/tracked_atomic_preference.h
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+// Copyright 2013 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.
+
+#ifndef CHROME_BROWSER_PREFS_TRACKED_ATOMIC_PREFERENCE_H_
+#define CHROME_BROWSER_PREFS_TRACKED_ATOMIC_PREFERENCE_H_
+
+#include <string>
+
+#include "chrome/browser/prefs/tracked_preference.h"
+#include "chrome/browser/prefs/tracked_preference_helper.h"
+
+// A TrackedAtomicPreference is tracked as a whole. A hash is stored for its
+// entire value and it is entirely reset on mismatch.
+class TrackedAtomicPreference : public TrackedPreference {
+ public:
+  TrackedAtomicPreference(
+      const std::string& pref_path,
+      size_t reporting_id,
+      size_t reporting_ids_count,
+      TrackedPreferenceHelper::EnforcementLevel enforcement_level);
+
+  // TrackedPreference implementation.
+  virtual void StoreHash(const base::Value* value,
+                         PrefHashStore* pref_hash_store) const OVERRIDE;
+  virtual void EnforceAndReport(
+      PrefHashStore* pref_hash_store,
+      base::DictionaryValue* pref_store_contents) const OVERRIDE;
+
+ private:
+  const std::string pref_path_;
+  const TrackedPreferenceHelper helper_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrackedAtomicPreference);
+};
+
+#endif  // CHROME_BROWSER_PREFS_TRACKED_ATOMIC_PREFERENCE_H_