Chrome 51.0.2679.0 
OSX 10.11.4

What steps will reproduce the problem?
(1) Visit https://permission.site
(2) Press Cmd-Ctrl-F. If the toolbar is visible, press Cmd-Shift-F
(3) Click on "Fullscreen"
(4) Observe the message "Press [Esc] to exit fullscreen"
(5) Press [Esc]

What is the expected output?
You exit fullscreen?

What do you see instead?
You're still in fullscreen!

This is the expected behaviour, but the string is misleading.

egm@ worked on the UI for this with ainslie@. Emily, could you take this on to figure out if it should be WontFix or if there's something else we should do?

Note that this is arguably an edge case on OSX. There was too much power user demand for "Presentation Mode" ( Issue 504573 ), so now we have "Always Show Toolbar in Fullscreen" as a workaround.
However, it is possible to initiate fullscreen from an extension, which could make this even more confusing (e.g. see  Issue 523604 ).