UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36
Platform: 7834.66.0 (Official Build) stable-channel lumpy

Example URL:

Steps to reproduce the problem:
1. Open NaCl DevEnv
2. Click on the three dots to mount a folder from Google Drive to mount point /mnt/local/test
3. see an error message on the console:
  mkdir '/mnt/local/test' failed: Operation not permitted
4. cd /mnt/local/test; ls
5. See the files there, so the directory obviously mounted

What is the expected behavior?
No error message when the directory can be mounted

What went wrong?
Misleading error message even though the directory successfully mounted.

Did this work before? N/A 

Chrome version: 49.0.2623.111  Channel: stable
OS Version: 
Flash Version: Shockwave Flash 21.0 0.197-r1