chromeos: changes how DisplayManagerObservers are notified

ui/display/display_list.h

Index: ui/display/display_list.h
diff --git a/ui/display/display_list.h b/ui/display/display_list.h
index 20a454d462520de777b0ad0ef15e3eede0c19c2f..295dc3fb57a0510f6c9088e6a2c1fa0da4d4e9d3 100644
--- a/ui/display/display_list.h
+++ b/ui/display/display_list.h
@@ -64,6 +64,8 @@ class DISPLAY_EXPORT DisplayList {
   // callers release the last lock they call the observers appropriately.
   std::unique_ptr<DisplayListObserverLock> SuspendObserverUpdates();
 
+  void AddOrUpdateDisplay(const Display& display, Type type);
+
   // Updates the cached display based on display.id(). This returns a bitmask
   // of the changed values suitable for passing to
   // DisplayObserver::OnDisplayMetricsChanged().