mash: Add a simple, temporary preferences store.

components/filesystem/directory_impl.cc

Index: components/filesystem/directory_impl.cc
diff --git a/components/filesystem/directory_impl.cc b/components/filesystem/directory_impl.cc
index 715c31f200c541f608fa351b1361221c0fdb65c5..8c86fc7043bb47dd7f9c2a4b6a260f79277d9e28 100644
--- a/components/filesystem/directory_impl.cc
+++ b/components/filesystem/directory_impl.cc
@@ -70,7 +70,7 @@ void DirectoryImpl::OpenFile(const mojo::String& raw_path,
 
   base::File base_file(path, open_flags);
   if (!base_file.IsValid()) {
-    callback.Run(FileError::FAILED);
+    callback.Run(GetError(base_file));
     return;
   }
 
@@ -203,7 +203,7 @@ void DirectoryImpl::IsWritable(const mojo::String& raw_path,
 void DirectoryImpl::Flush(const FlushCallback& callback) {
   base::File file(directory_path_, base::File::FLAG_READ);
   if (!file.IsValid()) {
-    callback.Run(FileError::FAILED);
+    callback.Run(GetError(file));
     return;
   }