[CUPS Printing] Fix |printing::PrintSettings::Clear| on CrOS.

This probably went unnoticed because it's only used in some error-handling
paths.

Bug: none
Change-Id: I2707a1ceb9ba303454bfb0b622ad404340e0d0db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1609827Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Vladislav Kuzkokov <vkuzkokov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659461}

printing/print_settings.cc

@@ -182,6 +182,12 @@ void PrintSettings::Clear() {
 #endif
   is_modifiable_ = true;
   pages_per_sheet_ = 1;
+#if defined(OS_CHROMEOS)
+  send_user_info_ = false;
+  username_.clear();
+  job_title_.clear();
+  pin_value_.clear();
+#endif  // defined(OS_CHROMEOS)
 }
 
 void PrintSettings::SetPrinterPrintableArea(