[webkit-gtk] Gamepad Support

[Michael Catanzaro]

All the Linux gamepad code was removed in 
http://trac.webkit.org/changeset/220532/webkit since it was never 
enabled by default and never updated to use Apple's new gamepad code 
instead of Google's older code.

Of course, all the cross-platform gamepad support still exists. It just 
needs to be implemented for the GTK and WPE ports.

I think we'd be fine with adding a dependency on your gamepad library 
as long as (a) it uses either a BSD/MIT style or LGPLv2+ (not LGPLv3+ 
and not GPL) license, and (b) as long as it's optional, so that distros 
can turn it off if they don't ship it yet. This means you'd need to use 
WEBKIT_OPTION_DEFINE to make ENABLE_GAMEPAD a public option in 
OptionsGTK.cmake.

I think all the code you'd need to modify is under 
Source/WebCore/platform/gamepad and Source/WebKit/UIProcess/Gamepad. 
There's gamepad code in a few other places, but it all looks 
cross-platform.

Michael