Componentize //chrome/browser/prefs/tracked.

chrome/browser/prefs/tracked/tracked_preference.h

-// 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.
-
-#ifndef CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_
-#define CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_
-
-class PrefHashStoreTransaction;
-
-namespace base {
-class DictionaryValue;
-class Value;
-}
-
-// A TrackedPreference tracks changes to an individual preference, reporting and
-// reacting to them according to preference-specific and browser-wide policies.
-class TrackedPreference {
- public:
-  virtual ~TrackedPreference() {}
-
-  // Notifies the underlying TrackedPreference about its new |value| which
-  // can update hashes in the corresponding hash store via |transaction|.
-  virtual void OnNewValue(const base::Value* value,
-                          PrefHashStoreTransaction* transaction) const = 0;
-
-  // Verifies that the value of this TrackedPreference in |pref_store_contents|
-  // is valid. Responds to verification failures according to
-  // preference-specific and browser-wide policy and reports results to via UMA.
-  // May use |transaction| to check/modify hashes in the corresponding hash
-  // store.
-  virtual bool EnforceAndReport(
-      base::DictionaryValue* pref_store_contents,
-      PrefHashStoreTransaction* transaction) const = 0;
-};
-
-#endif  // CHROME_BROWSER_PREFS_TRACKED_TRACKED_PREFERENCE_H_