Do not crash if no Account Info Preferences exist

components/signin/core/browser/account_tracker_service.cc

Index: components/signin/core/browser/account_tracker_service.cc
diff --git a/components/signin/core/browser/account_tracker_service.cc b/components/signin/core/browser/account_tracker_service.cc
index b1dc370db2b727dddebcc37796f50de2687905b8..fc97379bff0580b1ddd8f0ab31b3c681259d6d5f 100644
--- a/components/signin/core/browser/account_tracker_service.cc
+++ b/components/signin/core/browser/account_tracker_service.cc
@@ -308,6 +308,8 @@ void AccountTrackerService::MigrateToGaiaId() {
 void AccountTrackerService::LoadFromPrefs() {
   const base::ListValue* list =
       signin_client_->GetPrefs()->GetList(kAccountInfoPref);
+  if (list == nullptr)
+    return;
   std::set<std::string> to_remove;
   bool contains_deprecated_service_flags = false;
   for (size_t i = 0; i < list->GetSize(); ++i) {