[SyncFS] Add NULL check to SyncFileSystemService::DidInitializeFileSystemForDump

chrome/browser/sync_file_system/sync_file_system_service.cc

Index: chrome/browser/sync_file_system/sync_file_system_service.cc
diff --git a/chrome/browser/sync_file_system/sync_file_system_service.cc b/chrome/browser/sync_file_system/sync_file_system_service.cc
index b1e5b6b2432ef756e70b8327d5af201b92220070..28e66ddd706917fe92efd01ec40b5ff05a2ccdca 100644
--- a/chrome/browser/sync_file_system/sync_file_system_service.cc
+++ b/chrome/browser/sync_file_system/sync_file_system_service.cc
@@ -505,6 +505,11 @@ void SyncFileSystemService::DidInitializeFileSystemForDump(
 
   base::ListValue* files =
       GetRemoteService(origin)->DumpFiles(origin).release();
+  if (!files) {
+    callback.Run(new base::ListValue);
+    return;
+  }
+
   if (!files->GetSize()) {
     callback.Run(files);
     return;