1619515 - Add a macro to simplify writing runtime function detection wrappers

Status: NEW

(Firefox :: Session Restore, enhancement, P3)

Description

[Mike de Boer [:mikedeboer]]

This would reduce the amount code duplication and necessary copy-pasting whenever we have to use a private cocoa API, which have no guarantee of existing on all OSX versions Firefox runs on.

Examples in tree that would be helped by this macro:

https://searchfox.org/mozilla-central/rev/b7e3ec2468d42fa59d86c03ec7afeb209813f1d4/gfx/2d/CGTextDrawing.h#22-35
...and bug 440895 introduced a whole bunch more.

I'd be happy to look into this soonish, but it'd be my first time writing a macro, so I'm leaving it unassigned and please feel free to take it!