Add TrackedPreferenceValidationDelegate

chrome/browser/prefs/tracked/tracked_atomic_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_ATOMIC_PREFERENCE_H_
 #define CHROME_BROWSER_PREFS_TRACKED_TRACKED_ATOMIC_PREFERENCE_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "chrome/browser/prefs/pref_hash_filter.h"
 #include "chrome/browser/prefs/tracked/tracked_preference.h"
 #include "chrome/browser/prefs/tracked/tracked_preference_helper.h"
 
+class TrackedPreferenceValidationObserver;
+
 // A TrackedAtomicPreference is tracked as a whole. A hash is stored for its
-// entire value and it is entirely reset on mismatch.
+// entire value and it is entirely reset on mismatch. An optional observer is
+// notified of the status of the preference during enforcement.
 class TrackedAtomicPreference : public TrackedPreference {
  public:
-  TrackedAtomicPreference(
-      const std::string& pref_path,
-      size_t reporting_id,
-      size_t reporting_ids_count,
-      PrefHashFilter::EnforcementLevel enforcement_level);
+  TrackedAtomicPreference(const std::string& pref_path,
+                          size_t reporting_id,
+                          size_t reporting_ids_count,
+                          PrefHashFilter::EnforcementLevel enforcement_level,
+                          TrackedPreferenceValidationObserver* observer);
 
   // TrackedPreference implementation.
   virtual void OnNewValue(const base::Value* value,
                           PrefHashStoreTransaction* transaction) const OVERRIDE;
   virtual bool EnforceAndReport(
       base::DictionaryValue* pref_store_contents,
       PrefHashStoreTransaction* transaction) const OVERRIDE;
 
  private:
   const std::string pref_path_;
   const TrackedPreferenceHelper helper_;
+  TrackedPreferenceValidationObserver* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(TrackedAtomicPreference);
 };
 
 #endif  // CHROME_BROWSER_PREFS_TRACKED_TRACKED_ATOMIC_PREFERENCE_H_