Add a mojo bridge for PersistentPrefStore.

chrome/browser/prefs/chrome_pref_service_factory.h

Index: chrome/browser/prefs/chrome_pref_service_factory.h
diff --git a/chrome/browser/prefs/chrome_pref_service_factory.h b/chrome/browser/prefs/chrome_pref_service_factory.h
index 3743d9a898fe62c4f8209b08da4eee6c79cfc6ef..3d87614c4bd6dfcee0be84cf787109213ce28796 100644
--- a/chrome/browser/prefs/chrome_pref_service_factory.h
+++ b/chrome/browser/prefs/chrome_pref_service_factory.h
@@ -78,7 +78,8 @@ std::unique_ptr<PrefService> CreateLocalState(
 std::unique_ptr<sync_preferences::PrefServiceSyncable> CreateProfilePrefs(
     const base::FilePath& pref_filename,
     base::SequencedTaskRunner* pref_io_task_runner,
-    prefs::mojom::TrackedPreferenceValidationDelegate* validation_delegate,
+    std::unique_ptr<prefs::mojom::TrackedPreferenceValidationDelegate>*
+        validation_delegate,
     policy::PolicyService* policy_service,
     SupervisedUserSettingsService* supervised_user_settings,
     const scoped_refptr<PrefStore>& extension_prefs,