On Windows 10 I change my screen setup from two mirrored screens to two extended screens (essentially, adding a new screen to the system) the following DCHECK fires:

[18296:13616:0926/101756.831:FATAL:screen_win.cc(614)] Check failed: screen_win_displays_.size() == 0u (1 vs. 0)

The call stack:
>	display.dll!display::win::ScreenWin::GetScreenWinDisplay(const tagMONITORINFOEXW & monitor_info) Line 614	C++
 	display.dll!display::win::ScreenWin::GetPrimaryScreenWinDisplay() Line 597	C++
 	display.dll!display::win::ScreenWin::GetPrimaryDisplay() Line 444	C++
 	display.dll!display::win::ScreenWin::GetSystemMetricsForHwnd(HWND__ * hwnd, int metric) Line 341	C++
 	chrome.dll!BrowserDesktopWindowTreeHostWin::GetClientAreaInsets(gfx::Insets * insets) Line 102	C++
 	views.dll!views::HWNDMessageHandler::GetClientAreaInsets(gfx::Insets * insets) Line 1215	C++
 	views.dll!views::HWNDMessageHandler::OnWindowPosChanging(tagWINDOWPOS * window_pos) Line 2409	C++

It appears that this code runs before the corresponding WM_DISPLAYCHANGE/WM_SETTINGCHANGE has fired. (It fires almost immediately afterwards.)

Everything seems to be okay - the system updates properly when the display-change message fires.

Perhaps we should consider removing this DCHECK?