Integrate registry_hash_store_contents with the rest of tracked prefs.

components/user_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 COMPONENTS_USER_PREFS_TRACKED_TRACKED_PREFERENCE_H_
 #define COMPONENTS_USER_PREFS_TRACKED_TRACKED_PREFERENCE_H_
 
 class PrefHashStoreTransaction;
 
 namespace base {
 class DictionaryValue;
 class Value;
 }
 
+enum class TrackedPreferenceType : int32_t { ATOMIC = 1, SPLIT = 2 };
+
 // 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() {}
 
+  virtual TrackedPreferenceType GetType() const = 0;
+
   // 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.
+  // store. Performs validation and reports results without enforcing for
+  // |external_validation_transaction|.
   virtual bool EnforceAndReport(
       base::DictionaryValue* pref_store_contents,
-      PrefHashStoreTransaction* transaction) const = 0;
+      PrefHashStoreTransaction* transaction,
+      PrefHashStoreTransaction* external_validation_transaction) const = 0;
 };
 
 #endif  // COMPONENTS_USER_PREFS_TRACKED_TRACKED_PREFERENCE_H_