Google Chrome	53.0.2773.0 (Official Build) dev (64-bit)
Revision	ced2fcee2c85702055d028f4e3e48c5a75a7e41c-refs/heads/master@{#400610}
Platform	8481.0.0 (Official Build) dev-channel panther
Blink	537.36 (@ced2fcee2c85702055d028f4e3e48c5a75a7e41c)
JavaScript	V8 5.3.256
Flash	22.0.0.192-r1

To reproduce:
  Connect gnubby
  Open a web page that requires gnubby touch
  Verify web page accepts gnubby touch
  Open secure shell

Expected behavior:
  gnubby requests touch

Actual behavior:
  Failure with code 255

Notes:
  Logs from secure shell:
Loading NaCl plugin... done.
0706 11:52:09.208000: SSH forward helper not installed:
0706 11:52:09.218000: Specified native messaging host not found.
0706 11:52:09.471000: onMessageExternal listener: STATUS
0706 11:52:09.475000: request
0706 11:52:09.480000: sender
0706 11:52:09.529000: Enumerated 0 gnubbies
0706 11:52:09.530000: Enumerated 2 gnubbies
0706 11:52:13.436000: onMessageExternal listener: OPTIONS
0706 11:52:13.437000: request
0706 11:52:13.438000: sender
0706 11:52:13.674000: onMessageExternal listener: STATUS
0706 11:52:13.675000: request
0706 11:52:13.679000: sender
0706 11:52:13.693000: Enumerated 0 gnubbies
0706 11:52:13.696000: Enumerated 2 gnubbies
0706 11:54:10.855000: onMessageExternal listener: OPTIONS
0706 11:54:10.856000: request
0706 11:54:10.857000: sender
0706 11:54:11.001000: onMessageExternal listener: STATUS
0706 11:54:11.001000: request
0706 11:54:11.002000: sender
0706 11:54:11.003000: Enumerated 0 gnubbies
0706 11:54:11.004000: Enumerated 1 gnubbies
0706 11:54:11.017000: openDevice got lastError:
0706 11:54:11.017000: Failed to open device.
0706 11:54:11.017000: failed to open device. permissions issue?
0706 11:54:14.622000: onMessageExternal listener: GET_LOG
0706 11:54:14.623000: request
0706 11:54:14.624000: sender
ssh_exchange_identification: Connection closed by remote host
NaCl plugin exited with status code 255.

I have also noticed that the gnubby app has problems and have filed bug b/29943535