Move WriteFile and WriteFileDescriptor from file_util to base namespace.

printing/backend/cups_helper.cc

Index: printing/backend/cups_helper.cc
diff --git a/printing/backend/cups_helper.cc b/printing/backend/cups_helper.cc
index 5636f089476e9549fc702d4e7dd5ab06d13f3198..49334d4aa94422578b6cf12028d76a7096187b26 100644
--- a/printing/backend/cups_helper.cc
+++ b/printing/backend/cups_helper.cc
@@ -345,7 +345,7 @@ bool ParsePpdCapabilities(
     return false;
 
   int data_size = printer_capabilities.length();
-  if (data_size != file_util::WriteFile(
+  if (data_size != base::WriteFile(
                        ppd_file_path,
                        printer_capabilities.data(),
                        data_size)) {