[sync] Check against nullptr web_data_backend->GetDatabase()

components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc

Index: components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc
diff --git a/components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc b/components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc
index df12ab1add44935e2791a2fd862e767b7672585b..7049f31ff175fd672099ce2a8808716879d9b643 100644
--- a/components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc
+++ b/components/autofill/core/browser/webdata/autocomplete_sync_bridge.cc
@@ -448,6 +448,13 @@ void AutocompleteSyncBridge::ActOnLocalChanges(
 }
 
 void AutocompleteSyncBridge::LoadMetadata() {
+  if (!web_data_backend_ || !web_data_backend_->GetDatabase() ||
+      !GetAutofillTable()) {
+    change_processor()->ReportError(FROM_HERE,
+                                    "Failed to load AutofillWebDatabase.");
+    return;
+  }
+
   auto batch = base::MakeUnique<syncer::MetadataBatch>();
   if (!GetAutofillTable()->GetAllSyncMetadata(syncer::AUTOFILL, batch.get())) {
     change_processor()->ReportError(