Enable "Hide Extension" option when "Save Link As" on the Mac

content/browser/download/file_metadata_mac.mm

Index: content/browser/download/file_metadata_mac.mm
diff --git a/content/browser/download/file_metadata_mac.mm b/content/browser/download/file_metadata_mac.mm
index f4ae3c9750943adc0b88b14dfeafde35f09be680..79e9724d1f31b50636da687d2b0c26c0bdbbeec5 100644
--- a/content/browser/download/file_metadata_mac.mm
+++ b/content/browser/download/file_metadata_mac.mm
@@ -166,4 +166,15 @@ void AddQuarantineMetadataToFile(const base::FilePath& file, const GURL& source,
   }
 }
 
+void SetExtensionHiddenForFile(const base::FilePath& file, bool hidden) {
+  NSString* filePath =
+      [NSString stringWithUTF8String:file.value().c_str()];
+  if (filePath) {
+    NSDictionary* attributes = @{ NSFileExtensionHidden : @(hidden) };
+    [[NSFileManager defaultManager] setAttributes:attributes
+                                     ofItemAtPath:filePath
+                                            error:nullptr];
+  }
+}
+
 }  // namespace content