Add a mojo bridge for PersistentPrefStore.

chrome/browser/prefs/chrome_pref_service_factory.cc

Index: chrome/browser/prefs/chrome_pref_service_factory.cc
diff --git a/chrome/browser/prefs/chrome_pref_service_factory.cc b/chrome/browser/prefs/chrome_pref_service_factory.cc
index 2a9584cf5b5be91cdb7dbe28a7e26412f5bb8c45..13d6a4b96f6069b02bb0e7ae403444f568e7e02b 100644
--- a/chrome/browser/prefs/chrome_pref_service_factory.cc
+++ b/chrome/browser/prefs/chrome_pref_service_factory.cc
@@ -498,7 +498,8 @@ std::unique_ptr<PrefService> CreateLocalState(
 std::unique_ptr<sync_preferences::PrefServiceSyncable> CreateProfilePrefs(
     const base::FilePath& profile_path,
     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,
@@ -520,9 +521,11 @@ std::unique_ptr<sync_preferences::PrefServiceSyncable> CreateProfilePrefs(
   sync_preferences::PrefServiceSyncableFactory factory;
   scoped_refptr<PersistentPrefStore> user_pref_store(
       CreateProfilePrefStoreManager(profile_path)
-          ->CreateProfilePrefStore(pref_io_task_runner,
-                                   start_sync_flare_for_prefs,
-                                   validation_delegate));
+          ->CreateProfilePrefStore(
+              content::BrowserThread::GetTaskRunnerForThread(
+                  content::BrowserThread::IO),
+              pref_io_task_runner, start_sync_flare_for_prefs,
+              validation_delegate));
   PrepareFactory(&factory, profile_path, policy_service,
                  supervised_user_settings, user_pref_store, extension_prefs,
                  async);