Move ash specific cursor code to CursorManager.

ash/display/mouse_cursor_event_filter.cc

Index: ash/display/mouse_cursor_event_filter.cc
diff --git a/ash/display/mouse_cursor_event_filter.cc b/ash/display/mouse_cursor_event_filter.cc
index 2973ef8b545fc386963807c42496429dae372491..469db416c15aa664b9d6f859830ff0a6ea29da36 100644
--- a/ash/display/mouse_cursor_event_filter.cc
+++ b/ash/display/mouse_cursor_event_filter.cc
@@ -153,6 +153,8 @@ bool MouseCursorEventFilter::WarpMouseCursorIfNecessary(
   if (dst_root->bounds().Contains(point_in_dst_screen)) {
     DCHECK_NE(dst_root, current_root);
     dst_root->MoveCursorTo(point_in_dst_screen);
+    ash::Shell::GetInstance()->cursor_manager()->SetDeviceScaleFactor(
+        dst_root->AsRootWindowHostDelegate()->GetDeviceScaleFactor());
     return true;
   }
   return false;