Chromium	56.0.2912.0 (Build de développement) (64 bits)
Révision	81f338e0f394826ceabceddedbc570e806cb2c17-refs/heads/master@{#430191}

URLs (if applicable) : www.youtube.com
Other browsers tested:
  Add OK or FAIL, along with the version, after other browsers where you
have tested this issue:
     Safari:FAIL
    Firefox:OK
         IE:OK
no test with Opera or Chrome

What steps will reproduce the problem?
(1) the problem is very simple : I am not able to watch at high resolution videos (720/1080p, and 480) on youtube website


What is the expected result?
to have in the menu the possible item 480/720/1080

What happens instead?
nothing


Please provide any additional information below. Attach a screenshot if
possible.
test with other web browsers, as written at the begining.
other test on dailymotion video website and no problem with high definition.