Update ReplaceIllegalCharactersInPath to handle quirks in HFS+ and VFS

content/browser/download/save_package.cc

Index: content/browser/download/save_package.cc
diff --git a/content/browser/download/save_package.cc b/content/browser/download/save_package.cc
index 1211c7f71f158933c29bc1da4a6fe0375d82f6c8..8300c2d95b2b13d568acd91085b973af4d129fb1 100644
--- a/content/browser/download/save_package.cc
+++ b/content/browser/download/save_package.cc
@@ -1242,7 +1242,7 @@ base::FilePath SavePackage::GetSuggestedNameForSaveAs(
     name_with_proper_ext = EnsureHtmlExtension(name_with_proper_ext);
 
   base::FilePath::StringType file_name = name_with_proper_ext.value();
-  base::i18n::ReplaceIllegalCharactersInPath(&file_name, ' ');
+  base::i18n::ReplaceIllegalCharactersInPath(&file_name, '_');
   return base::FilePath(file_name);
 }