This is faster and more straight-forward code than the old
ShouldUseDarkScrollbar shenanigans, and allows to have dark-themed
scrollbars.
Differential Revision: https://phabricator.services.mozilla.com/D138077
We have this situation right now where all the themes are inheriting from
nsNativeBasicTheme. Rename it to a nicer name, and clean up some code while at
it.
In the future I'd like to simplify the inheritance chain to remove
nsNativeTheme altogether (so that all nsITheme implementations use
mozilla::widget::Theme).
That's not hard to do mechanically, but rather than dumping all of
nsNativeTheme into Theme I'd like to do it a bit more carefully, to hopefully
remove a lot of the helpers that nsNativeTheme has to deal with XUL and so on
and use something nicer. Eventually the inheritance chain will be something
like:
* nsITheme : public nsISupports
* Theme : public nsITheme, public nsITimerCallback, public nsINamed
* ThemeCocoa : public Theme
* nsNativeThemeCocoa : public ThemeCocoa
* nsNativeThemeWin : public Theme
* nsNativeThemeGtk : public Theme
Differential Revision: https://phabricator.services.mozilla.com/D135668