ScreenHelperWin is the platform dependent part of the original
nsScreenManagerWin and nsScreenWin. It listens the WM_DISPLAYCHANGE
message and pushes updates to ScreenManager. See patch part 4. for how
ScreenManager works.
MozReview-Commit-ID: 20A3ZQKmH9a
--HG--
rename : widget/windows/nsScreenManagerWin.cpp => widget/windows/ScreenHelperWin.cpp
rename : widget/windows/nsScreenManagerWin.h => widget/windows/ScreenHelperWin.h
extra : rebase_source : a3058c237d38f72103251802ab5f5bbd672e9b70