Integrate registry_hash_store_contents with the rest of tracked prefs.

components/user_prefs/tracked/tracked_atomic_preference.h

Index: components/user_prefs/tracked/tracked_atomic_preference.h
diff --git a/components/user_prefs/tracked/tracked_atomic_preference.h b/components/user_prefs/tracked/tracked_atomic_preference.h
index 04bd0eaae8520c091810d376ba1ca5e918f0e133..e279af859474b44baae94f4bca49b7076b26c2bd 100644
--- a/components/user_prefs/tracked/tracked_atomic_preference.h
+++ b/components/user_prefs/tracked/tracked_atomic_preference.h
@@ -30,10 +30,13 @@ class TrackedAtomicPreference : public TrackedPreference {
                           TrackedPreferenceValidationDelegate* delegate);
 
   // TrackedPreference implementation.
+  TrackedPreferenceType GetType() const override;
   void OnNewValue(const base::Value* value,
                   PrefHashStoreTransaction* transaction) const override;
-  bool EnforceAndReport(base::DictionaryValue* pref_store_contents,
-                        PrefHashStoreTransaction* transaction) const override;
+  bool EnforceAndReport(
+      base::DictionaryValue* pref_store_contents,
+      PrefHashStoreTransaction* transaction,
+      PrefHashStoreTransaction* external_validation_transaction) const override;
 
  private:
   const std::string pref_path_;