Handle modified displays in mustash.

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 df748457c63eb85f196094e1f8a9915682d1874e..c280fd44b491631dcd6244d73cf96741e84a783b 100644
--- a/ui/display/display_list.h
+++ b/ui/display/display_list.h
@@ -65,8 +65,11 @@ class DISPLAY_EXPORT DisplayList {
   // callers release the last lock they call the observers appropriately.
   std::unique_ptr<DisplayListObserverLock> SuspendObserverUpdates();
 
-  // Updates the cached id based on display.id() as well as whether the Display
-  // is the primary display.
+  // Updates the cached display based on display.id().
+  void UpdateDisplay(const display::Display& display);
+
+  // Updates the cached display based on display.id(). Also updates the primary
+  // display if |type| indicates |display| is the primary display.
   void UpdateDisplay(const display::Display& display, Type type);
 
   // Adds a new Display.
@@ -88,6 +91,8 @@ class DISPLAY_EXPORT DisplayList {
   void IncrementObserverSuspendLockCount();
   void DecrementObserverSuspendLockCount();
 
+  Type GetTypeByDisplayId(int64_t display_id) const;
+
   std::vector<display::Display> displays_;
   int primary_display_index_ = -1;
   base::ObserverList<display::DisplayObserver> observers_;