Profile::IsIncognitoProfile() currently returns false for CEF incognito profiles
because they are not the primary OTR profile. At the same time, we don't
necessarily want IsIncognitoProfile() to return true for CEF profiles because,
among other things, that causes the BrowserView to apply the dark toolbar theme.
Instead, this change updates ProfileMenu expectations to support the CEF
incognito profiles without otherwise modifying the incognito behavior.
Note that the IsIncognitoProfile() implementation has recently changed in
https://crrev.com/7bf6eb2497 and the conclusions in this commit will likely need
to be revisited in an upcoming Chromium update.
