Move DisplayManager and DisplayChangeObserverX11 from aura to ash.

ui/gfx/screen_win.cc

Index: ui/gfx/screen_win.cc
diff --git a/ui/gfx/screen_win.cc b/ui/gfx/screen_win.cc
index 072f47a6458165233752b1f5e6dec5b7f9de32f8..9b33c6b20024f5154671e19c4e3202ef20917952 100644
--- a/ui/gfx/screen_win.cc
+++ b/ui/gfx/screen_win.cc
@@ -90,6 +90,14 @@ gfx::Display ScreenWin::GetPrimaryDisplay() const {
   return display;
 }
 
+void ScreenWin::AddObserver(DisplayObserver* observer) {
+  // TODO(oshima): crbug.com/122863.
+}
+
+void ScreenWin::RemoveObserver(DisplayObserver* observer) {
+  // TODO(oshima): crbug.com/122863.
+}
+
 HWND ScreenWin::GetHWNDFromNativeView(NativeView window) const {
 #if defined(USE_AURA)
   NOTREACHED();