[SyncFS] Fix chrome://syncfs-internals callback handling

chrome/browser/ui/webui/sync_file_system_internals/extension_statuses_handler.cc

Index: chrome/browser/ui/webui/sync_file_system_internals/extension_statuses_handler.cc
diff --git a/chrome/browser/ui/webui/sync_file_system_internals/extension_statuses_handler.cc b/chrome/browser/ui/webui/sync_file_system_internals/extension_statuses_handler.cc
index 1e2ee7a8db4738d7028bd36b8bb986468ec8965d..9573f87249d430d05d61fa29793eef236656b65a 100644
--- a/chrome/browser/ui/webui/sync_file_system_internals/extension_statuses_handler.cc
+++ b/chrome/browser/ui/webui/sync_file_system_internals/extension_statuses_handler.cc
@@ -81,13 +81,17 @@ void ExtensionStatusesHandler::GetExtensionStatusesAsDictionary(
 
   sync_file_system::SyncFileSystemService* sync_service =
       SyncFileSystemServiceFactory::GetForProfile(profile);
-  if (!sync_service)
+  if (!sync_service) {
+    callback.Run(base::ListValue());
     return;
+  }
 
   ExtensionService* extension_service =
       extensions::ExtensionSystem::Get(profile)->extension_service();
-  if (!extension_service)
+  if (!extension_service) {
+    callback.Run(base::ListValue());
     return;
+  }
 
   sync_service->GetExtensionStatusMap(base::Bind(
       &ConvertExtensionStatusToDictionary,