Add ENABLE(SCROLLING_THREAD) and use it to turn off some code we don't need for iOS

[Simon Fraser (smfr)]

Add ENABLE(SCROLLING_THREAD) and use it to turn off some code we don't need for iOS

[Simon Fraser (smfr)]

Created attachment 391825 [details]
Patch

[Simon Fraser (smfr)]

Created attachment 391830 [details]
Patch

[Simon Fraser (smfr)]

Help getting Nicosia to build would be appreciated.

[Zan Dobersek]

Comment on attachment 391830 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=391830&action=review

> Source/WTF/wtf/PlatformEnable.h:475
> +#if !defined(ENABLE_SCROLLING_THREAD)
> +#define ENABLE_SCROLLING_THREAD 0
> +#endif
> +

This block is not specific to any platform, so here the ENABLE_SCROLLING_THREAD gets defined for everybody but Cocoa which handles it in PlatformEnableCocoa.h.

> Source/WTF/wtf/PlatformEnable.h:831
> +#if !defined(ENABLE_SCROLLING_THREAD) && USE(NICOSIA)
> +#define ENABLE_SCROLLING_THREAD 1
> +#endif

Hence, this block does nothing for Nicosia-using ports. If the above block is removed, and ENABLE_SCROLLING_THREAD gets defined to 1 here, everything seems to build and work fine for Nicosia-using ports.

For this patch, I would propose using only this block to define ENABLE_SCROLLING_THREAD (if it was not defined before) to either 0 or 1, depending on USE(NICOSIA). I can swoop in later to introduce PlatformEnable<Port>.h files that handle this for everybody possibly defining USE(NICOSIA), and putting back the above block.

[Simon Fraser (smfr)]

What's odd here is that NICOSIA isn't a platform, nor is it an OS feature, and there is no #define USE_NICOSIA 1 in the header files; it all comes in from cmake. That makes the pattern of #defines in PlatformUse.h a bit weird.

[Simon Fraser (smfr)]

Created attachment 391876 [details]
Patch

[Simon Fraser (smfr)]

https://trac.webkit.org/changeset/257578/webkit

[Radar WebKit Bug Importer]

<rdar://problem/59855388>