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

content/browser/download/file_metadata_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/download/file_metadata_mac.h"
 
 #include <ApplicationServices/ApplicationServices.h>
 #include <Foundation/Foundation.h>
 
 #include "base/files/file_path.h"
@@ skipping 148 matching lines @@
 
   OSStatus os_error = LSSetItemAttribute(&file_ref, kLSRolesAll,
                                          kLSItemQuarantineProperties,
                                          quarantine_properties);
   if (os_error != noErr) {
     OSSTATUS_LOG(WARNING, os_error)
         << "Unable to set quarantine attributes on file " << file.value();
   }
 }
 
+void SetExtensionHiddenForFile(const base::FilePath& file, bool hidden) {
+  NSString* filePath =
+      [NSString stringWithUTF8String:file.value().c_str()];
+  if (filePath) {
+    NSNumber* boolNumber = [NSNumber numberWithBool:hidden ? YES : NO];

[Avi (use Gerrit), 2015/12/12 00:41:46]

bool ? YES : NO is not useful; bools convert as 1 and 0, which are YES and NO.

Couldn't you just do "@(hidden)" below?

[shrike, 2015/12/16 19:04:12]

Acknowledged.

+    NSDictionary* attributes =
+        [NSDictionary dictionaryWithObject:boolNumber
+                                    forKey:NSFileExtensionHidden];

[Avi (use Gerrit), 2015/12/12 00:41:46]

NSDictionary* attributes = @{ NSFileExtensionHidden : @(hidden) };

should work.

[shrike, 2015/12/16 19:04:12]

Done.

+    [[NSFileManager defaultManager] setAttributes:attributes
+                                     ofItemAtPath:filePath
+                                            error:nullptr];
+  }
+}
+
 }  // namespace content