exo: Fix cursor scaling for 1.25 DSF

ui/display/manager/managed_display_info.h

Index: ui/display/manager/managed_display_info.h
diff --git a/ui/display/manager/managed_display_info.h b/ui/display/manager/managed_display_info.h
index 0a2863aaa30718c652fea8b8e501aacb488d6fdb..e52e05e248c4e6a540f4da41187bd83f661b40d6 100644
--- a/ui/display/manager/managed_display_info.h
+++ b/ui/display/manager/managed_display_info.h
@@ -227,6 +227,10 @@ class DISPLAY_MANAGER_EXPORT ManagedDisplayInfo {
   // Returns the rotation set by a given |source|.
   Display::Rotation GetRotation(Display::RotationSource source) const;
 
+  // Returns a measure of density relative to a display with 1.0 DSF. Unlike the
+  // effective DSF, this is independent from the UI scale.
+  float GetDensityRatio() const;
+
   // Returns the ui scale and device scale factor actually used to create
   // display that chrome sees. This can be different from one obtained
   // from dispaly or one specified by a user in following situation.